Errors in geography: When Mike is in Idaho he has a clear view of Mt. Hood. Not only is the mountain too far away to see (over 200 miles), there is another mountain range lying between Idaho and Mt. Hood, blocking the view.
Errors made by characters (possibly deliberate errors by the filmmakers): When Scott is spotted exiting his limo, Bob says, "If it isn't Scottie Favor... dressed in a three-piece suit..." In the next frame Scott walks towards the camera with his Italian wife wearing a double-breasted two-piece suit.
Crew or equipment visible: When Bob approaches Scott in the bar near the end of the film, two marks of black gaffer tape can be seen on the floor.