Gary enters Rockford's motel room at night intending to kill Warren. The view through the window is day. The view though the window is day the entire few minutes that Gary is in the room looking for Warren and fighting with Rockford. When Gary and Rockford exit the motel room a few minutes later and are arrested, it is night again.
When Rockford is being interviewed by the federal agent early in the episode, the agent attempts to tape record the conversation. He presses the "Play" button on his recorder, but he does not press the "Record" button that is right next to it. Tape recorders of that era, however, all required that both the "Play" and "Record" buttons be pushed simultaneously in order to record a conversation.
During the car chase, footage of Warren's Pacer is obviously sped up.
Jim turns up to interview Gary. He is having trouble with his car and when Jim turns up he says 'I called the auto club but they haven't turned up yet.' When he realizes it's Jim he says 'oh Rockford, I thought you were the auto club.' Nobody would say that first sentence if they thought it was the auto club. (Note: Obviously Gary's putting on an act, knowing full well Rockford was approaching, randomly spouting out that first sentence as a cover).