Continuity mistake: When the bus is brought out of the hangar for its maiden trip, the top of the front of the bus just clears the top of the roof. When it parks outside, the rear section has a glass roof which wouldn't clear the roof without damaging either the bus or the hangar roof.
The Big Bus (1976)
1 continuity mistake - chronological order
Directed by: James Frawley
Starring: Stockard Channing, Rene Auberjonois, John Beck, Joseph Bologna
Factual error: At the start of the movie, the nuclear-powered articulated bus that is attempting a non-stop land run to Denver leaves New York City, but you can see the Rocky Mountains in the background.
Parking Lot Doctor: Please sign this, absolving me of any responsibility for the results of treatment.
Kitty Baxter: But you're a Doctor.
Parking Lot Doctor: And I intend to remain one.
Trivia: At the Iron Man's house, there is a painting of the Hindenburg airship disaster. Rene Auberjonois (Father Kudos) had previously starred in the 1975 movie The Hindenburg as Major Napier.