Factual error: When the neighbor is showing off his Challenger he states it is a 1972. That year Challenger had a different grill. The car he has is either a 1970 or 1971.
Other mistake: During Hutch's flashback to when he was about to assassinate the man who skimmed $1 million, he says he was holding an H&K .45. However, at that exact moment you can see "9mm" on the side of the gun.
Continuity mistake: In one scene after Hutch is beaten up on the bus, he has no facial injuries. Then in the next scene, they are back.