Factual error: Early the movie, the maroon 1972 Monte Carlo at the intersection in the background is sporting wheels from a 1984 IROC Camaro Z28.
Factual error: When Ritchie was following the driver with $20k into NYC, the scene shows the GWB entrance heading to NJ.
Factual error: The movie takes place in the late 1960s/early 1970s, but during Richie's pursuit of the Bronco, trains of R142 subway cars, not introduced until 2000, can be seen in the background. (01:11:15)
Factual error: In the scene where Frank Lucas drives to meet Nicky Barnes, a 2002 Lincoln town car as well as an NYPD traffic cop redirecting traffic are visible. (01:44:25 - 01:45:00)
Factual error: A few moments after the 20% rent deal for $1 in the cafe you can see a 747-400 (or later) in the sky, the winglets identify it as such. The 747-400 had its maiden flight in April 1988. That scene plays in 1968.
Factual error: As Lucas is leaving the bar to make a call to Saigon, a modern blue car passes outside, seen through the curtains. (01:51:55)
Answer: The idea is if cops wouldn't take a million dollars for themselves, free and clear without risk, they are impeccably honest. Therefore, they wouldn't accept bribes and probably not hold still for shakedowns or payoffs. They wouldn't cover up drug or weapon planting and would testify against crooked cops.