Shared with you
The conversation between Thornton and the diving coach about the Triple Lindy was only half-fictional. Rodney Dangerfield actually spent some time in the 50's as an acrobatic diver in Atlantic City, and there really was a diving horse in the 40's (ended before Rodney's diving career) - this entire scene was created after Dangerfield talked about the horse with scriptwriter Michael Elias, who then passed it onto director Alan Metter and they wrote it up. However the Triple Lindy was never a real dive. Dangerfield was also an excellent swimmer, and the movie incorporated a pool scene at the beginning to show this as well.
Like his character, in his youth, Rodney Dangerfield was an acrobatic high diver in real life.
When Thornton talks to Kurt Vonnegut Jr. over the phone, the last thing he says before hanging up is "Next time, I'll call Robert Ludlum!" Spy novelist Ludlum was one of Rodney Dangerfield's real-life neighbors at the time.
During the scene where Thornton is in Professor Turgeson's history class, and where Turgeson picks up the desk and throws it across the room while yelling at Thornton, if you look really closely you can see that Rodney Dangerfield is laughing while Sam Kinison is yelling at him, trying to get him to answer the question about the Korean War. This take was ultimately left in the movie, because Dangerfield had such a hard time keeping a straight face during his scene with Kinison that eventually Alan Metter decided to leave him laughing from a far distance in the final cut.
In the original script, Rodney Dangerfield's character was poor, but Harold Ramis suggested that it be changed to make him rich.
This was the sixth highest-grossing film of 1986, and the second highest-grossing comedy of the year after Crocodile Dundee (1986).