Ben Mendelsohn and Ryan Reynolds in "Mississippi Grind"

It was in the time spent away from the Iowa set of their 2007 baseball drama “Sugar” that Anna Boden and Ryan Fleck stumbled onto another game, boarding a riverboat casino and becoming fascinated with the gamblers who were taking others for a ride. For the co-directors who first rose to prominence with “Half Nelson,” the cardsharps at the poker tables and the chancers at the roulette wheel held an undeniable appeal, grounded in the earthly circumstances that so many of their protagonists have found themselves in while having the enchanting possibility of turning around their fortunes in a matter of seconds.

There isn’t anything ironic about the rainbow you see as the first image in “Mississippi Grind,” Boden and Fleck’s latest film, which doesn’t only infer the role luck will play for Gerry (Ben Mendelsohn) and Curtis (Ryan Reynolds), the inveterate gambler and thrillseeker, respectively, who find each other over a hand of cards, but the array of color the filmmakers once again bring to bear in their study of men whose reach just exceeds their grasp. While Gerry is gifted with cards, he’s naturally less so with his finances and any relationship lasting more time than he’ll usually spend playing cards, which is why he seems to take so easily to Curtis, who is prone to saying “It’s Macchu Picchu time” when things get the least bit serious, just before disappearing.

Things head south for the pair, both literally and figuratively, as they make their way down the Mississippi River, rumbling through pool halls, brothels, race tracks and casinos, with an ostensible goal of paying off Gerry’s debts by hitting a jackpot. But for both the characters and the audience, the time spent in each other’s company seems to be the real reward, with Mendelsohn and Reynolds exuding a laid-back charm that makes them so dangerous as competitors since you can never tell when they’re bluffing — indicative of the casual vibe that “Mississippi Grind” aspires to, inspired by the knockabout buddy pictures of the 1970s such as “Scarecrow” and “California Split.” You could describe the film as easy, going down smoothly like a good bottle of bourbon, yet in terms of storytelling Boden and Fleck rarely take the path well-traveled, acknowledging the scrappy lives Gerry and Curtis have made for themselves while seeing the magic in it.

During the Toronto Film Festival, the two spoke about how “Mississippi Grind,” their first film in a much-too-long five years came together, how they were inspired by real locations and finding the right guys to play their leads.

Ben Mendelsohn and Ryan Reynolds in "Mississippi Grind"How did that opening image of a rainbow come about?

Anna Boden: When we were writing this script, we took the journey our characters take. We drove between Iowa and New Orleans and hit up casinos and dog tracks and horse tracks and tried to live this journey. On our way, we were playing in a poker tournament at a casino in Mississippi and one of the things we loved about doing that was meeting all of the characters that actually play there. There was one character that said something that just stuck with us. I was at a table with him and he said, “I drove to the end of a rainbow once. There wasn’t nothing there. It just faded out into the trees.” It felt like such a perfect metaphor for these two guys traveling trying to get to the end of the rainbow and find their pot of gold. That really stuck with us. It ended up as a line in the script, but more importantly, it ended up as a theme for the movie.

Did you develop these two guys as reactions to each other or separately? It seemed to me that Gerry had skill and Curtis had luck, but both had found their limits.

Ryan Fleck: I don’t think we thought it through that much. Obviously, we spent a lot of time on the script and thinking through these characters and what they represent. We really wanted to explore a magical element in the movie and we wanted Ryan Reynolds’ character to represent that in some way because he is the handsome leprechaun that Gerry is looking for in his life. When he walks into the room and behaves the way he does, Gerry is just in awe of this guy who seems like he can do no wrong, like “this is the guy that’s going to get me out of the hole I’m in.” Of course, Ryan is more than what he looks like on the surface and he has his own flaws too, so it’s nice to see that unravel as the film progresses.

Anna Boden: The movie was always conceived as a relationship between these two characters, but it wasn’t about these two guys separately as much as what happens when they come together — what they mean for each other, what they reflect in each other, and in that way, I think we did always think about them in conjunction.

Obviously, there’s a version of this story that might not be considered so magical. How did the magic come in?

Anna Boden: When you are dealing with gamblers, they are such superstitious people. They believe in signs, good luck coins and charms, so it felt right for this movie to have an element of is there luck? Is there magic? Or isn’t there? And to have that question be posed maybe in the form of Ryan Reynolds.

Ben Mendelsohn and Ryan Reynolds in "Mississippi Grind"After your first three films that centered on characters with the rest of their lives ahead of them, was it interesting to start from the perspective of people who have already lived some life?

Anna Boden: Ben Mendelsohn’s character certainly has that, but Ryan Reynolds’ character comes on and for the first three-quarters of the movie, you feel like he might not have a past at all. He might have just come out of thin air, conjured for Gerry’s benefit, so playing with that idea of how much of our character’s lives are determined by the past and how much we can lift ourselves out of that, in Ryan’s case, was part of the story of the movie and the journey that they travel.

Did you cast them separately or did you know what kind of chemistry they would have beforehand?

Anna Boden: We met them separately and loved them both. We had a pretty good idea that they’d probably get along just based on what we felt from both of them, but we had to just cross our fingers that first of all they liked each other as human beings, and secondly that they had that chemistry as actors. We got them together in New Orleans a couple weeks before we started shooting and we were just blown away by how quickly they hit it off. They are both very fast and very funny. Ben has this wild mind that is going in a million different places at once and Ryan can just keep up with it. It was really fun to watch.

How did you figure out that brilliant opening shot where their characters are introduced with Jerry sitting down at the poker table just as Curtis is coming up the escalator from afar?

Ryan Fleck: That shot was conceived out of location scouting and that’s a real poker room in a casino. We fell in love with it. Once we saw the glass and the way the poker table was configured, we were both like, “Okay, great.” We put Gerry right here [at the table], he sits, and we zoom pass him and Curtis comes right up the escalator and boom. But we actually lost that location very close to the last minute and we were devastated because of that shot. The shot said so much about the kind of movie we were making. You know, referencing [Robert] Altman and that ’70s vibe. It aligns the characters without cutting. Thankfully, we were able to convince the casino to let us shoot there, so we got the shot. It didn’t take that long. We did maybe eight takes of it and it was actually fairly simple actually once you start to do it.

Anna Boden: Once we got the timing and the cuing right, it took a few rehearsals, then from there, it was just about people remembering their lines.

Since you mentioned the ‘70s vibe, you’ve said “Scarecrow” was an influence – did that have an impact on the loose feel of this?

Ryan Fleck: Huge. The rapport and the unpredictable nature of the relationship that Gene Hackman and Al Pacino have in that movie is just phenomenal. Gene Hackman is on the verge of slugging somebody every five minutes in that movie and you just don’t know when he is going to do it. I feel like we tried to put an element of that in this movie, an unpredictable volatile nature in both these characters that is done so beautifully in that movie. Hopefully, we pulled that off in this one too.

Is it true you were able to shoot the New Orleans section of the film first and then go on the actual road trip the characters take?

Ryan Fleck: We shot it out of sequence just by the necessity of the budget and we couldn’t do the actual trip itself. That would have just taken too long and been too costly for the movie like this. But it’s a road picture and we needed to see those changing textures of the landscape. We’re really proud of the fact that you see snow on the ground when we’re in Iowa. When they are driving from St. Louis on south, they are actually on the highway from St. Louis to Memphis so that was important.

Anna Boden: Part of our process of going on that journey ourselves was locating what those few locations are that say everything, that you couldn’t find in New Orleans, that you couldn’t fake. For those places that we need to be in the actual location for, we prioritize that and work with our producers to make that happen.

Ben Mendelsohn and Ryan Reynolds in "Mississippi Grind"You also shoot in clubs and make music a major part of the film. Why was that important?

Ryan Fleck: Once we got the idea for the movie and we said, “We are going to take this journey down south,” it just screamed blues. But it’s a genre of music we hadn’t known much about, so it felt like the right time to learn. We basically took a crash course in blues. We had a friend, who loved music, send us a playlist of thousands of songs. In pre-production, we sifted through it all and fell in love with this music. Fortunately, we were able to use a large amount of it in the movie.

How did the James Toback cameo come about?

Ryan Fleck: Because we are referencing so many of those movies, we couldn’t think of a more perfect way to reference cinema about gambling than the author of the original “Gambler.” We know James a little bit through some circles in New York and he is just one of those guys that’s filled with stories about old Hollywood in the 70’s and 80’s, making movies. He is a great storyteller. And we thought it would be fun to have this iconic director punch out our lead.

“Mississippi Grind” opens on September 25th at the Angelika in New York, October 2nd at the Sundance Sunset in Los Angeles and will expand in the weeks ahead. A list of cities and dates can be found here.