The Miss Budweiser raced through the film in its all-red color scheme, which was not adopted by the team until 1994. As one of the most recognizable boats in the history of hydroplane racing, this mistake may have been made deliberate by filmmakers.
When Jim and the mayor are in the high school gym trying to sell the townspeople on hosting the Gold Cup race, the basketball court has 3-point lines. Those did not exist in high school basketball until 1987.
Film takes place in 1971. When Mike sees a celebrity at the Miami race, he asks another kid if that's Grizzly Adams. The kid says yes, it's Dan Haggerty. Haggerty didn't introduce the Grizzly Adams character until 1974 in the film "The Life and Times of Grizzly Adams" (and the TV Show was 3 years later).
Early in the movie, The Space Needle is shown in an aerial shot prior to the 1971 races in Seattle. The Kingdome is visible in the background. The stadium didn't open until 1976 and ground wasn't even broken on construction until November of 1972.
The film depicted the schedule as follows; Miami, Florida; Chicago; Seattle, Dayton, and Madison. The actual schedule of 1971 was as follows: Miami, Florida; Washington, DC, Owensboro, Kentucky; Detroit, Michigan; Madison, Indiana; Tri City, Washington; Seattle, Washington; Dexter, Oregon; Dallas, Texas. No races occurred in Chicago at the year the film took place.