For the bank robbery sequences, Tyler Hoechlin (Michael Sullivan, Jr.) had to learn to drive, something he was only too happy to do. Hoechlin mastered it all easily, but, just to be on the safe side, a stunt driver was sitting in the back, with his own set of driving controls.
Notice that Michael Sullivan, Jr. isn't eating his pie and ice cream in the diner, when he and his father are talking about the money. According to Sam Mendes, in earlier takes, Tyler Hoechlin gobbled up his pie, not considering that he would have to perform the scene again and again. By the time they got to the take that's in the film, Hoechlin was stuffed, and couldn't take another bite. Tom Hanks, by contrast, knew to put small amounts of food into his mouth and eat slowly.
Maguire's crime scene photography work is based on Arthur "Weegee" Fellig, a famous crime scene photographer in the 1920s and 1930s, who was licensed to possess a "scanner" radio that allowed him to listen to frequencies used by the police and fire departments. This enabled him to arrive (by car) at crime and fire scenes, sometimes before the authorities did, as if informed by telepathic powers, to which his nickname, a corruption of "Ouija", alludes. He sold his photos to tabloid newspapers. The photos in Maguire's apartment are real 1930s crime scene photos, some of which were taken by "Weegee".
The shot of the reporter drawing a gun and approaching the Geneva Hotel, shows a grocery store behind him. In reality, it is a Starbucks that was covered up and closed for four days. It was used as the craft service area, and the employees were kept on to serve the crew (and Tom Hanks) coffee.
The film is set in 1931, and Costume Designer Albert Wolsky had real trouble finding distinctive clothing from the period. As this was the height of the Depression, fashions lacked the flamboyance of the 1920s, and the style of the later 1930s, when gangsterism was "fashionable". Failing to find any usable real clothes from 1931, Wolsky came across a weaver in upstate New York, who was able to make all of the required clothes, using the same weight of fabrics that were used in that period. Once woven, the costumes then had to be aged and dyed.
Anthony LaPaglia filmed a scene in which he played Al Capone, but it was decided to leave Capone off-screen, and so his scene was deleted. LaPaglia is listed first in the "Special Thanks" section of the credits as a result. LaPaglia played Frank Nitti in Frank Nitti: The Enforcer (1988).
One of the locations for one of the bank robberies was physically perfect, but the wrong way around. There was only room to shoot from right to left and not vice versa. So Dennis Gassner and his team had to dress the location, reversing street signs, license plates, and even switching steering wheels on all of the cars.
One day, when Cinematographer Conrad L. Hall was setting up a shot of Paul Newman, Hall looked through his viewfinder and began to cry. When asked what was wrong, he just said, "He was so beautiful. He was so beautiful."
Prior to the brief travel scene along the "Road to Perdition", with Michael Sullivan, Jr. (Tyler Hoechlin) hanging out a car window as they near their destination, the local road commission oiled the gravel surface of rural road, shoulder-to-shoulder, to prevent dust clouds. But when filming began, the Model A was attached to an equipment trailer pulled by a large utility truck, and a member of the crew was squatting near the rear of the antique car armed with a canister and making fake dust.
Producer Dean Zanuck had never seen a graphic novel before, until he was pitched the idea of "Road to Perdition". Flipping through the pages of the novel, he was immediately hooked. He then sent a copy to his father, Richard D. Zanuck, who was in Morocco at the time. He was also smitten with the project, and instructed his son to dispatch a copy of the novel to Steven Spielberg, who called back two days later, saying that he wanted to do it.
Paul Newman had an assist with his accent from Irish writer Frank McCourt, the author of "Angela's Ashes", who gave him a tape of him speaking. McCourt has lived in the U.S. for many years, but still has some vestiges of his native Irish accent, which is what Newman wanted to emulate.
According to author Max Allan Collins, the "Road to Perdition" graphic novel was an American homage to the manga series "Lone Wolf and Cub" by Kazuo Koike. Collins quoted Koike at the beginning of the book: "You must choose a road for yourself".
Temperatures occasionally dropped to -30 degrees Fahrenheit (-34.4 degrees Celsius) while filming took place. This didn't necessarily mean that they had all the snow they required. The special effects department still had to make many tons of the fake stuff.
The photographs shown in Harlen Maguire's (Jude Law's) apartment also appear in a book by Luc Sante titled "Evidence". According to Sante, the photos are part of a collection held by the Municipal Archives of the City of New York, and were taken by members of the NYPD during the years of 1914 to 1918.
Due to their similar first names, the two Sullivans (father and son) obviously share the same initials; interestingly, they're also played by actors with the same initials: Tom Hanks and Tyler Hoechlin.
In the beginning of the film, when Rooney (Paul Newman) is teaching Michael (Tyler Hoechlin) and Peter (Liam Aiken) dice, and pretends to lose, he says that he can spot a hustler anywhere. Paul Newman played "Fast Eddie" Felson in The Hustler (1961) and The Color of Money (1986).
Paul Newman and Tom Hanks have been in Disney Pixar movies. Hanks was in the Toy Story franchise as Sheriff Woody, and Newman was in Cars (2006) as Doc Hudson, who's character made flashback appearances in Cars 3 (2017).
The trivia items below may give away important plot points.
Up until the killing in the warehouse, Michael Sullivan, Jr. (Tyler Hoechlin) has little access to his father. Consequently, Sam Mendes made sure that the father figure was always filmed from afar, or through doorways and mirrors, to emphasize this distance. Once father and son find themselves on the run, this changes, and close-ups are employed more and more frequently.
At the end of the film, Tyler Hoechlin's character goes to live with the elderly farmer couple that they had met earlier. Tyler Hoechlin would later go on to play the character of Superman, a character whose origin usually consists of him being adopted by the Kents, another elderly farmer couple.