Factual error: Mahony gets Can$15,000 from the bank he works in in Canada and flies to Atlantic City (US) where the cashier gives him US$15,000 of chips. US and Canadian dollars are not equivalent and, at the end of 1981, the cashier should be giving him less than US$13,000. Since he is broke, he couldn't have made up the difference himself.
Continuity mistake: The Toronto cop asks someone on the phone to get the flight plan for the casino's private jet, and gives an aircraft registration. In the very next shot we see Mahowny getting out of the plane in Atlantic City, and the registration number on its engine cowl is completely different.
Factual error: Early on Mahoney is sitting in his car in the garage of Toronto Terminal 1. The time frame is 1980. There's a view of planes on taxiway and runway, it shows Canadair regional jets and Airbus A320's. Two planes that had not been invented in 1980. Not a big deal, but not historically correct.