Due to Rodney Dangerfield's contractual obligations with the Miller Brewing Company and his appearances in Miller Lite beer commercials at the time, only Miller beer was allowed to be shown in certain scenes (when Dangerfield goes to get a beer out of the refrigerator during the party at his house and during the large party at the college when the police arrive with extra beer).
Rodney Dangerfield always looked out for younger comedic talents. He was a big proponent for Sam Kinison's part as a crazed professor in Back to School. They also considered Jim Carrey, but he was rejected as too young. Later when producer Chuck Russell got the chance to direct The Mask (1994), he was finally able to use Jim Carrey, transforming the Mask from a "very dark horror film" to a comedy.
Kurt Vonnegut Jr. played himself in a cameo for the film in which he is hired by Thornton Melon to write a paper on the topic of the novels of Kurt Vonnegut. As a joke, recognizing the work as not Melon's own, Professor Turner tells him, "Whoever did write this doesn't know the first thing about Kurt Vonnegut."
Alice Cooper's song "The Great American Success Story" (on the album 'Constrictor') was apparently intended to be the theme song. Its lyrics summarize the plot and include "he don't get no respect", and the chorus leads off with the phrase "back to school." The song was not used in the film, and there is no mention of the connection in the liner notes of the album.
During the scene where Thorton 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 Korea conflict. 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 it took so many tries for him to not laugh, and eventually Alan Metter decided to leave him laughing from a far distance in the final cut.
It was Rodney Dangerfield's idea for his character Thornton Melon to go back to school as a rich man. Once that was suggested no one involved in this movie could imagine him going back to school any other way.
The University of Wisconsin-Madison, University of Southern California, and California State University, Los Angeles teamed up to portray the fictional Grand Lakes University. The one college Rodney Dangerfield applied to for his higher education was the University of Wisconsin. He said, "It took 40 years, but I finally got here."
Before the end credits, the message "For ESTELLE Thanks For So Much" is shown. This is a dedication to Estelle Endler, one of the executive producers of the film, who died during filming. She was Rodney Dangerfield's long-time manager, who helped him get into films such as Caddyshack (1980).
Bob Saget was briefly considered for the role of Professor Turgeson due to his friendship with Rodney Dangerfield, however Dangerfield did not feel that he was hard-edged and shocking enough to portray the character. He then suggested to director Alan Metter, Sam Kinison for the role, and it was eventually given to him.
The professor doing studies on the chimpanzees is named Dr. Berazini whose last name is very similar to that of Bobby Berosini who was famous in the 80's and 90's for a Las Vegas act that featured performing orangutans.
William Zabka and Rodney Dangerfield first met early one morning in a Madison, Wisconsin hotel elevator. Dangerfield wore a blue robe with his hair sticking up. After Zabka introduced himself he asked Dangerfield why he was in a robe. "I gotta get in the sauna," Dangerfield replied. "I gotta get the pot out of my lungs." [Laughs.] "You, you're young. You can handle it, but me I gotta get it out."
Sally Kellerman got the impression that the star of the movie was a "very serious guy on set." She noted that he wrote notes in his script every night, sitting in his robe.
A husband-and-wife screenwriting team claimed they wrote the basic plot of the movie in their screenplay Second Season, which they submitted to Orion Pictures in 1979. Alan Metter sued Orion for not paying him all he said he was due. Rodney Dangerfield later counter-sued for suing without reasonable cause. Casting director Caro Jones sued the producers and said she did not receive full pay or the proper screen credit.
In an interview with The A.V Club, William Zabka revealed that he tried to make Chas funnier and less of a bully. "So I actually put on a funny walk and I had a scarf a bunch of times. I made him way more funny than he actually turned out in the film. They cut out most of my funny. In fact, the director [Alan Metter] pulled me aside one day and said, 'We need you to be more like the guy you did in The Karate Kid (1984). You're coming off too likable and funny.'"
Terry Farrell's character, Valerie Desmond, has a difficult time understanding Astronomy in this film, while later in Terry Farrell's career, playing in Star Trek: Deep Space Nine (1993), Terry plays "Lt. Commander Jadzia Dax" who's character holds numerous degrees including one in Astrophysics.
Sally Kellerman admitted to Orange Coast Magazine in November 1986 that she "didn't really know who Rodney Dangerfield was," only having seen him in his Miller Lite commercials. Therefore she "wasn't just flipped out of my mind at being the woman who lifts him up. I thought, 'Oh, whoopee! You're going to get to play his love interest.' Ye gods, I knew I'd made it." But the two got along. "The second day we met, he said, 'Did you change your hair?' And I said, 'No, did you?' After that I liked him so much. He's such an odd guy."