After reading the script, Robin Williams originally wanted to play the Barney-like dinosaur. He later opted to play the doctor. Ironically, he played doctors-in other fields of medicine-for "Awakenings" (1990) & "Patch Adams" (1998). He also starred opposite Edward Norton's Barney-like performer in "Death to Smoochie" (2002).
Grant's arrest in Los Angeles (June 27, 1995), and his subsequent appearance on The Tonight Show starring Jay Leno, two days before the release of this movie, not only boosted the box-office take, despite unfavorable reviews, it also catapulted Leno's ratings over and above rival David Letterman's for the very first time.
Before Chris Columbus worked with Robin Williams on Mrs. Doubtfire (1993), he had seen him in comedy clubs in Los Angeles, where he was blown away by his energy. He thought him one of the most impressive minds in comedy.
A blonde actress named Betsy Monroe plays the girlfriend of Jeff Goldblum's character at the beginning of this film. She is the same actress who catches the amorous attention of Robin Williams' character during the pool scene in Mrs. Doubtfire.
The second film in the trilogy with director Chris Columbus & actor Robin Williams, which all feature San Francisco as the main setting, a city both Columbus and Williams were residents. The trilogy began with Mrs. Doubtfire, this film and Bicentennial Man as the concluding film.
As Hugh Grant is talking to the doctor, the name plate on the door reveals that the doctor's surname is Thatcher. This may be a nod to the fact that Grant is a British subject, since Margaret Thatcher is a late Prime Minister of England.