Planes do not operate on the same frequencies as CB radio, neither do they carry regular CB aboard as the frequencies used interfere with the navigation equipment.
Spider's directional antenna is not connected to a co-ax cable and spins loosely on the roof, making it impossible for his radio to pick up a signal. Also, his car radio does not have an RF meter, making detecting the signal impossible.
When Electra talks on her radio the modulation light is not synchronized with her voice.
When Spider and Cochese are in Spider's car after pulling down the Nazis' antenna, Cochese says, "Oh Spider, I don't think I can take much more of this," but his lips aren't moving.
Reflected in the window of Spider's house when Pam runs up to help and Blaine answers the door.
Reflected in the driver's-side window when Warlock is at the riverfront.
Set in Union, Nebraska, the Chevron station is branded Standard in the film. Chevron did not use the Standard brand outside of the west and parts of the southeast. Amoco, not Chevron, had the rights to the Standard name in Nebraska.