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)
Revealing mistake: Frank pulls up to his buddy's house where he's offered a bribe of a ski chalet. When he gets out of the car there are visible snow flurries. The scene moves to the living room that overlooks a lake. The trees are all lush and green in the background - obviously not winter.
Suggested correction: That was Richie, not Frank, who was offered the bribe.