Trivia: John Travolta made up the "cool dude walk" that Danny uses in the first scenes, when trying to create a bad boy image.
Trivia: The moment where Blutarski breaks the guitar and then apologises was unscripted, and improvised by John Belushi.
Trivia: Jeff East, who plays teenage Clark Kent, was dubbed over with Christopher Reeves' voice. The only time Jeff's actual voice is heard is when he shouts in excitement after jumping past the speeding train.
Trivia: Though Phil Silvers is shown prominently in the credits, he has only about 2-3 seconds of screen time at the end of the movie. Silvers suffered a stroke in the early 70's; "The Cheap Detective" was made in 1978. His speech had become slurred and likely affected his performance abilities.
Trivia: Maggie Smith is the only actress to win an Oscar for playing a character who loses an Oscar.
Trivia: In the opening title sequence we see a garbage truck going through the Golden Gate Bridge toll booth. We would find out later that these trucks were used to transport the pods. The truck is traveling southbound from Marin County into San Francisco which is appropriate, (intentional or not) since the book Body Snatcher was set in Mill Valley, in Marin County, about 10 miles from the bridge.
Trivia: Kenneth Williams initially turned down the role of Emile Prevert as he considered the script "offensive." But after numerous rewrites, he changed his mind.