Factual errors: Rolling Stones "I can't get no satisfaction" was _not_ on the Voyager 1 & 2 disks - "Johnny B Goode" by Chuck Berry was.
Continuity: When Starman and Jenny are sitting in her car, looking at the map projection, it projects in the wrong direction on their faces. When the camera is behind them, Starman is sitting on the East coast side of the map, but when the camera faces him the West coast is projected on his face.
Anachronisms: The two aircraft scrambled to intercept the UFO were Convair F-102A Delta Daggers. The F-102 was removed from service in 1976, eight years before the release of this film.
Factual errors: The jet that shoots at the UFO was a Northrop F-20 Tigershark, a fighter prototype that never entered military service. Upon close inspection, one can see the civilian aircraft registry number on the rear of the fuselage.
Continuity: Because of the location of the police car and the fact that Jenny Hayden is sitting in the passenger seat, she should be shot through her right cheek. But when Starman is healing her, the bullet wound is visible in her left cheek and there is no sign of injury at all on the right side of her face.
Continuity: The kidnapped note "Jenny" leaves on the bathroom mirror changes from the first time we see it, to when "Starman" comes back in to get it.
Miscellaneous: It isn't surprising that "Chequamegon" is mispronounced throughout this film: The Chequamegon National Forest is sometimes referred to as "that unpronounceable national forest" by those who don't live in its general vicinity. In the movie, they pronounce it "She-mogg-wahn", and the actual pronunciation is "Shih-KWAH-muh-gone".
Continuity: In the scene where Starman and Jenny are struggling for a gun in the car, Starman is wearing a wedding ring visible in one shot that is not seen again throughout the movie.
Factual errors: Sgt. Lemon, the crew chief on board the C&C helicopter wears the insignia of the 82nd Airborne Division on his right shoulder (indicating combat service). This has been worn with the "Airborne" tab since the end of World War I. Additionally all of the soldiers wear the "First US Army" patch on their left shoulder - the 1st US Army at the time was a headquarters unit at Fort Meade Maryland. And while it makes sense that the C&C chopper would be fitted out this way (Fort Meade is the home of the NSC) it doesn't make sense that the combat forces detailed to them in the southwest US would not be wearing their local insignia.