- Breakthrough Hit: For The Farrelly Brothers.
- California Doubling:
- Harry and Lloyd are supposed to be in Aspen, Colorado in the second half of the movie. However, a careful viewer will notice that they're actually in Breckenridge, not Aspen. While both towns have ski resorts, Breckenridge has one main street where shops and restaurants are located with cross streets descending the hills on the east and west sides of the valley feeding into the main drag, whereas Aspen is spread out across many blocks with rather busy traffic.
- In the scene where Harry and Lloyd are on the bed in the presidential suite, crying and blowing their noses with money, they are watching a commercial for Pacific Bell. If they are in a hotel in Aspen, there is no way they would have seen that commercial on a hotel TV when the ad is clearly for a company that serves the west coast. (U S WEST, now CenturyLink, was the Baby Bell in Colorado.) Then again, given that they're in a fancy resort in the Rocky Mountains, they almost certainly are watching satellite TV rather than cable or broadcast.
- The skiing scenes were clearly shot at Copper Mountain, not at an Aspen ski area. You can tell because the lift operators obviously wear Copper Mountain uniforms, not Aspen uniforms. Copper Mountain is over two hours drive from Aspen.
- The airport scenes in Rhode Island were filmed at Salt Lake City International Airport. In addition, Park City, Utah, doubles as Aspen during a few scenes set in town. Lloyd and Harry's apartment building is located in Salt Lake City, as is the building where Lloyd picks up Mary to drive her to the Airport. Finally, the building in Lloyd's dream sequence where he gives Mary her briefcase (and takes a peek at her rear) is La Caille, a gourmet restaurant and winery located just outside of Salt Lake City.
- Cast the Runner-Up: Jim Carrey was originally offered the role of Harry and was told that it had more drama. He chose the role of Lloyd because it had more laughs.
- Creator Killer: Thanks to the Disney/ABC deal killing any chance at success it had, the Dumb and Dumber cartoon would be the last Saturday morning cartoon made by Hanna-Barbera, which spent the rest of its (official) existence primarily as a production house for Cartoon Network.
- Dueling Dubs: The original and most widespread Brazilian dub was made in São Paulo, while the TV debut earned another dub from Rio. The leads of the latter returned in the sequel.
- Dyeing for Your Art: Lloyd's chipped tooth is real - Jim Carrey had chipped his years previously, and had it uncapped for this film.
- Jeff Daniels also got his hair naturally frizzy that way by not conditioning, blow drying, or combing his hair for two months.
- Enforced Method Acting: Jim Carrey's early life was hard because his family struggled with poverty, even living together in a van for a while. When Lloyd had to give a similar monologue about his life being in a rut, Jim teared up for real because it hit so close to home.
- Missing Trailer Scene: Two of them:
- (when being pursued by the cops) "I have an idea. Go..... FASTER!!!"
- An alternate take of the "It's okay! I'm a limo driver!" scene, with Lloyd still moving as he says it.
- Orphaned Reference: A deleted scene explains Lloyd's "I have rapist's wit" line. When Barnard (the Aspen hotel employee seen when Harry and Lloyd pull up in the Lamborghini) confuses Lloyd's sincere request for Boone's Farm as sarcasm, he remarks "you have a rapier (sharp) wit, sir." Had the scene made the theatrical cut, it would have simply made Lloyd a Malaproper and not carry Unfortunate Implications.
- Playing Against Type: Jeff Daniels was not a comedic actor before he made this film, but the Farrelly Brothers convinced the studio to let them have Daniels in their movie when they watched Something Wild.
- Daniels had done comedic films before (such as Arachnophobia), but he was often cast as the lead or straight man. This was his first opportunity to actually let his comedic chops loose.
- Romance on the Set: Jim Carrey and Lauren Holly married after meeting on this film, but it lasted less than a year.
- Screwed by the Network: The animated series had the misfortune of premiering on ABC just as it was being acquired by Disney, meaning it and the network's other shows save The Bugs Bunny and Tweety Show and the already Disney-owned The New Adventures of Winnie the Pooh (both of which were nothing but reruns at that point anyway) lost any and all support they might've otherwise had, as executives were more interested in running Disney-owned product.
- Star-Derailing Role: Averted, thankfully. Jeff Daniels was warned by his numerous people that if he took the part, his career was over. Never happened.
- Throw It In!: Jim Carrey threw in quite a bit, like "We landed on the moon!" and even "the most annoying sound in the world" (with the latter, you can clearly see Jeff Daniels and Mike Starr trying to hold it together, bracing for whatever Carrey was about to do; Daniels fails and loses his shit right before it cuts to a close-up of Starr).
- Also, "Big Gulps, huh? Alright!...Well, see ya later!"
- Wag the Director: The planned original ending was to have Harry and Lloyd get on the bikini tour bus. Jim Carrey convinced the Farrellys that the ending as filmed would be funnier and fit the two characters better.
- What Could Have Been:
I remember getting a phone call one day. My manager said, "There's a film. They want to use "Loser" as the theme song". There was a long pause, and he said, "The name of the film is Dumb and Dumber". And I just remember: That sums up what the world thinks of me at this point. I tried to have fun with it, tried to not take it too serious. But at the same time, it was a little disheartening sometimes.
- Nicolas Cage and Gary Oldman were the original choices to play Harry and Lloyd.
- Steve Martin and Martin Short both turned down the role of Lloyd. Mike Myers and Eddie Murphy were also considered.
- Rob Lowe turned down the role of Harry. Chris Farley was also considered.
- At one point, the Farrelly Brothers considered Corey Feldman for Lloyd and Corey Haim for Harry, but New Line Cinema CEO Robert Shaye wouldn't allow it as he felt the Coreys were no longer bankable actors.
- An entire subplot was filmed involving Mary's kidnapped husband Bobby being kept in a wooden shipping crate, but was ultimately discarded. The brief scene where Nicholas and Shay discuss the snow owl incident had originally led into a scene where Bobby manages to escape while still inside the crate.
- An early draft of the film had Mel Gibson as Mary's husband, playing himself in a cameo role. This was going to be a gag because at the time, Mel Gibson was one of Hollywood's biggest heartthrobs, and somebody like Lloyd Christmas couldn't possibly hope to compete with him.
- John Hughes wrote an unproduced draft of the script. Due to the deal he made with the directors, his name was to be stripped from the project, including the script.
- Trey Parker and Matt Stone were originally greenlit to write the script for the prequel, but changed their minds and returned all the money they were given (1.5 million dollars) to New Line Cinema.
- Beck had been approached about including "Loser" on the soundtrack, but he refused. He recalled the process:
- The Wiki Rule: The Dumb and Dumber Wiki.
Trivia / Dumb and Dumber