Ace Ventura compares Ray Finkle's room to Hannibal Lecter's prison cell from The Silence of the Lambs (1991). 17 years later, in Inside the Actors Studio: Jim Carrey (2011), Jim Carrey recounted that he asked Anthony Hopkins to dinner and discovered that his approach to Ace Ventura was the same as Hopkins' to Hannibal Lecter: they moved like animals. Carrey based Ventura's movement on birds and Hopkins based Lecter's movements on reptiles. Carrey confessed that Hopkins was becoming Hannibal Lecter right at the table.
The voice of Ace Ventura and the manner in which he speaks, was added by Jim Carrey only after several read throughs of the script. The voice was something Carrey used in his stand up routine. The "All righty then" was the catch phrase of one of his stand up characters and after the lines from the script weren't feeling right, he added it to the script and read through it again using that voice for all the lines. It was such an improvement that it became the main Ace Ventura personality trait.
The entire scene where Ace Ventura claims to be expert dolphin trainer Heinz Getwellvet was originally cut out of the theatrical release. It was added back in when the movie was released on videotape in June 1994, and was advertised as "additional footage not seen in theaters".
Jim Carrey uses the same voice and mannerisms for his In Living Color (1990) sketch character, Overly Confident Gay Man, as he did for Ace Ventura. In one of the sketches, he even uses the "Alrighty Then" phrase.
At the police station, Ace tells Einhorn, "I've come to confess. I was the second gunman on the grassy knoll." This was probably a joke about James Files, a convicted felon who in 1994 came forward as one of JFK's assassins. His claims have since been debunked.
Originally Ace wasn't written to be animal-related, but more of a generic Sherlock Holmes parody. Screenwriter Jack Bernstein came up with the pet detective idea after watching a David Letterman sketch about pet owners.
According to Courteney Cox, while filming her sex scene with Jim Carrey, all the animals in Ace's apartment had to be chained down. "But the squirrel would get loose and jump on the penguin. The penguin would bite the cockatoo and soon all hell would break loose and I'd find myself under the blanket with a macaw."
There was supposed to be a scene after Ace crashed his car while chasing Dan Marino's kidnappers. The white pigeon landed on his car, he got it singing "I got the white pi-geon! I got the white pi-geon". Then, in a parody of The Birds (1963), he is surrounded by birds that started tearing him apart. Then he wakes up with a big "whew." It was removed from the finished film since it was too dark.
The ass-talking scene started in In Living Color (1990). Frustrated one day with Keenen Ivory Wayans' constant rejection of his pitched sketches, Jim Carrey stood up and read a sketch from his butt, in Wayans's direction. The two almost fought before Wayans walked out of the room. "Later, we sat down, talked, and everything was cool," Wayans said.
According to Tom Shadyac in the DVD commentary, Jim Carrey came up with "Alrighty then" and other lines specifically because he thought they might catch on. The hand gesture Ventura gave before leaving the police station was also something Carrey intended to become popular. It did not.
Jim Carrey revealed on Inside the Actors Studio (1994) that he based Ace Ventura on a smart bird. "A cockatiel or a parakeet of some kind. The clothing I picked was all ... like a colourful bird, a tropical bird. The walk was bird-like. Everything was about a bird, when I spoke ... Everything was based on a bird, even the hairstyle."
In the movie, the Dolphins play the Super Bowl at Joe Robbie Stadium, their home field. In reality (as of the 2015 NFL season), no NFL team has played a Super Bowl in its home stadium as NFL rules prohibit teams from playing a Super in their own stadium.
When Ace is first informing Lt. Einhorn about his Ray Finkle theory, on the desk there are two apples and a banana positioned in a suggestive manner. This foreshadows the fact that Lt. Einhorn is actually the male Finkle.
The Crying Game (1992) parody wasn't in the screenplay, as it was not released until production on Ace Ventura was already under way. Using the music and the idea for parodying it was a last-minute decision.
The film was heavily criticised by the LBGT community for being homophobic and transphobic in its handling of a transgender villain and Ace's reaction to kissing her. Tom Shadyac defended this joke after some anti-defamation groups got on his case about it, saying that it was less about making fun of transpeople and more about how easily Ace will break from simply kissing another man despite all of his endeavors.