Factual error: When Jenny Hayden and Starman accidentally overshoot their destination and arrive in Las Vegas, Jenny discovers that her wallet is missing. She has no cash, no credit cards, and no identification whatsoever. The only money she has is a single quarter. Starman uses the quarter to hit the jackpot on a 25-cent slot machine, then uses the prize money to play the Horseshoe $500,000 slot machine, which he also wins. They then use the giant jackpot money to purchase a brand new Cadillac and drive it off the lot. Huge problem: In 1984 (and today), you could never collect a giant Las Vegas jackpot without several pieces of personal identification, for tax purposes. Likewise, you could never purchase and drive a brand new Cadillac off the lot without multiple pieces of identification and a financial disclosure statement (if paying cash).
Continuity mistake: The weather changes at least twice during the end sequence at Meteor Crater. Take a look at the clouds in the background of all of the shots, especially those looking at the San Francisco Peaks (near Flagstaff, AZ). The extreme long shots of the helicopters coming show dark clouds, while the wide shots show a mix of cloud free and then cloudy skies.