The distance Dan's green car is from the curb when he stalls out changes between camera shots.
The craps table that Mahowney plays at in Atlantic City has the "Big 6" and "Big 8" bets. These bets were never approved in Atlantic City and have never appeared on the layout of any of the city's craps tables.
In the scenes where several yellow Metro Toronto Police cars appear together, at least three different shades of yellow paint are visible. (The police changed to white and blue cars a few years after the period of the movie because the yellow paint they'd been using was withdrawn; presumably the filmmakers could not find enough cars of the right shade.)
In Toronto, with no other source of large sums of money, Mahowny converts a customer's $200,000 withdrawal to $300,000 to steal the excess. Yet when he arrives in Atlantic City, the cage person acknowledges his payment of $100,000. In 1980, $100,000 US would have cost at least $115,000 Canadian.
While listening to sports scores on the radio shortly after his arrest in 1982, the sportscaster gives the score of the Montreal Alouettes game. The Alouettes folded after the 1981 season. The current Alouettes began playing in 1996.
Movie takes place in 1980-1982, however Air Canada jets seen
in the background at the airport are painted in a design first introduced in the mid-to-late-'90s.
Even though the movie takes place in 1982, the Le Biftheque
Steak House restaurant is clearly visible in several of the opening scenes. That restaurant did not open in Toronto until 1999.
The Chevrolet Caprice driven by Lock is a late-'80s to 1990 model. The film is set in 1982.
When they drive to Niagara Falls at the end of the movie a modern style Chrysler minivan can be seen in a driveway in the background. The problem is the very first Chrylsler minivan was released in 1983, and even then they were square looking.
At 0:22:59 When casino manager says that mister Mahowney would like ribs and a coke camera markers can be seen on the carpet when he leaves.