Continuity mistake: In the scene where Harry and Tommy are sitting in the living room, Sally comes by with a drink for Tommy and the shot changes when she is behind Harry and walking towards Tommy. But in that next shot, Tommy is already holding the drink.
Visible crew/equipment: When Dick wants to go along with Mary to a wedding he tries to convince her. When he says "Whatever it takes, I'll do it" he walks forward. Take a look at the top of the screen and you'll notice the shadow of the boom mic on the wall following him.