Continuity mistake: Right before Richard discovers that Bernie is dead and Larry is talking about drugs becoming a career, "I watch the news. I read." There is a side/back view of Larry talking and neither his gestures or his mouth line up with what he is saying.
Continuity mistake: At the end of the movie, when the hitman comes to kill Bernie for one last time, Larry, Gwen, and Richard start running from the hitman and Gwen has her hat in her hand. They run over to the stereo and she drops it somewhere over by there. In later shots, however, you can see Gwen's hat lying right next to Bernie in front of the staircase.
Continuity mistake: In some scenes you can see Bernie breathing and blink his eyes when he is supposed to be dead.
Continuity mistake: When Larry and Richard are piling into the crowded elevator Monday morning with everyone, some of the people who get on are different from whom we see riding up. In particular we see the door close on a girl in brown with a green purse strap before she can get on, but she is seen riding in the elevator in the next shot.
Revealing mistake: When Larry and Richard are dragging the two bodies to the closet the first one lifts up his legs for Richard to put him in.
Continuity mistake: At the end of the movie, when the ambulance is shown backing up to Bernie's house, you can see a stretcher on the boardwalk that gets bumped and rolls down. This stretcher has Bernie on it, yet when it is bumped it is completely empty.
Continuity mistake: When Richard is using the phone to call the police, Larry's hand comes into the frame to hang up the phone. His sleeve is pulled up exposing his arm. In the next shot when they're in the entire frame, his sleeve is down.
Continuity mistake: Just after the hit man kills Bernie he proceeds to disguise himself and pulls a folded, floppy beach hat out of his pocket. Yet when we see him getting on the boat in the next scene the same folded hat is now a perfectly round, structured hat with a brim.
Factual error: In the lunch scene outside their office, Larry and Richard are at the food stand and notice Bernie walking into a building. The entrance awning reads "East 70th Street". As they walk away the street sign behind them reads "52nd Street". Apparently they must have superhuman vision which allows them to see 18 blocks away.