- Actor-Shared Background: Like Tommy, Chris Farley also graduated from Marquette University in Wisconsin.
- Dyeing for Your Art: David Spade refused to let any stylist touch his hair during the filming of the movie, and also avoided combing or using a hair dryer off the set to make his character look perpetually stressed.
- Enforced Method Acting: David Spade and Chris Farley were on again, off again friends, right up until Farley's passing, but because of numerous tensions (see Hostility on the Set) they really were driving each other nuts during the making of this film.
- Fake American: Dan Aykroyd (Ontarian by birth) takes a Superfans-esque Chicago accent in playing Zalinsky.
- Hostility on the Set: According to David Spade, he and Chris Farley got into a physical altercation on the set. Spade had gone out for a drink with Rob Lowe the night before. Farley had become very jealous and angrily repeated "How's Rob Lowe?". David got so fed up with Chris hounding him on the subject that he threw his Diet Coke on him, to which Chris responded by throwing David into a wall and down the stairs. After the fight, Spade walked off the set and refused to continue filming. In another incident, also arising due to Farley's jealousy, Farley stomped down hard on Spade's hand. The pair would sometimes go for hours without talking to each other, talk to each other through the director, etc.
- Romance on the Set: The gorgeous blonde woman who goes skinny-dipping in the motel swimming pool ended up dating Chris Farley for a while after she was introduced to him by David Spade. However, David Spade had his own romantic designs on her and was reportedly not happy about his Just Friends status.
- Throw It In!: While there are probably other examples, "Does this make me look fat?" "No, your face does" is confirmed to have begun as an ad-lib.
- Uncredited Role:
- Rob Lowe. He turned down being billed as he didn't want to have to pay Screen Actors Guild fees for being in the film.
- Fred Wolf worked on the screenplay uncredited.
- What Could Have Been:
- The director had every intention of deleting the scene in which Tommy and Richard triumphantly drive back to Sandusky while singing along to the radio, believing it didn't work. An editor felt the scene was at least worth finishing before making that decision, and the director found it actually did work with audible music, deciding to keep it in. A WCHB we can be grateful didn't happen!
- Christian Slater was considered for Richard. Chris Farley pushed for one of his two SNL co-stars to play Richard: David Spade, or Adam Sandler. Sandler wound up shooting Billy Madison instead, so Spade got the role.
- The character of Helen the Waiter was originally written for Roseanne Barr, but she was unavailable.
- Scheduling conflicts almost forced Rob Lowe to drop out of the film. This resulted in the filmmakers holding impromptu auditions while the movie was already filming for the part of Paul Barish. Matthew McConaughey was one of the actors who auditioned. Eventually, Lowe's scheduling conflicts were resolved and he was able to appear.
- Farrah Fawcett was considered for Beverly.
- Working Title: Billy the Third: A Midwestern. However Lorne Michaels was also working on Billy Madison and insisted the change. Other names considered included Fat Chance and XL before settling on Tommy Boy. It was shot under the title Rocky Road.
Trivia / Tommy Boy