The roller coaster crash that kicks off the film was significantly more graphic, with flying bodies and gore as the cars derail and topple over. The sequence was toned down considerably to avoid an "R" rating.
The filmmakers were originally going to include a scene of the young man on the phone with his mother, to establish a motive behind his plot, namely to get the money from larger amusements parks that were forcing his parents' small family-owned amusement park out of business. The filmmakers decided that the movie was more suspenseful if the motive behind the young man's actions were never known. It would also keep the audience from sympathizing with the young man's situation.
This was the third film presented in "Sensurround", a special low-frequency bass speaker setup consisting of four huge speakers loaned by distributors to select theaters showing the film. The system was employed only during certain sequences, and it was so powerful that it cracked plaster at some movie theaters. Four other Universal films used Sensurround: Earthquake (1974), Midway (1976), Battlestar Galactica (1978), and Mission Galactica: The Cylon Attack (1979). Alien (1979) had a limited release in 70 mm with Sensurround.
The roller coaster featured in the climax of the movie is the Revolution at Six Flags Magic Mountain in Valencia, California. It opened in 1976, and was the first roller coaster to feature a complete 360-degree vertical loop.
In 1976, both Tiger Beat and 16 magazines reported that Bay City Rollers would appear in this film. Instead, the band that performs is Sparks. Ironically Sparks' music video Sparks: Music That You Can Dance to (1985) was played at the night club Videopolis at Disneyland.