California Doubling: The film's suburban scenes take place in Vista del Mar, Nevada; but they were shot in Florida. Averted with the Las Vegas scenes, as they are shot there.
Harpo Does Something Funny: Given that toddlers don't generally take direction well, Rick Moranis was allowed to ad-lib and improvise extensively in his scenes opposite them to help the production come up with workable takes.
The Other Darrin: Everyone from the Japanese dub of the first film was recast. For example, Wayne Szalinski, voiced by the late Kei Tomiyama in the original, is now voiced by Issei Futamata.
Throw It In!: Literally with the scene where Adam pulls a giant peppermint out of his pocket and it lands on a car. One of the toddler twin actors pulled out a piece of candy from his pocket and tossed it aside, so the filmmakers decided to incorporate it into the movie.
Working Title: Was originally going to be a standalone movie called Big Baby before it became a Dolled-Up Installment sequel to Honey, I Shrunk the Kids. They were then going to call it Honey, I Blew Up The Baby but feared they'd get negative feedback.
General trivia
The only installment of the Honey, I Shrunk the Kids franchise not to have the word "shrunk" in the title.
Also the only installment of the Honey, I Shrunk the Kids franchise to feature all five Szalinskis: Wayne, Diane, Amy, Nick, and Adam.
Shortly before the film's release; Disney was sued by Paul Alter, best known as a frequent director for Mark Goodson Productions; specifically his work as the original director during the initial run of Family Feud during the 1970s and early 1980s and having been at that time the director on The Price Is Right from 1986 until 2000. Alter had submitted a similar script titled "Now, That's a Baby" to Disney in 1980 based upon watching his granddaughter toppled a set of blocks, with Alter's script having gotten an unspecified treatment, though nothing further came of the Alter submission. Alter's lawsuit alleged the film's plot (story by Garry Gordlow; who worked on the screenplay version alongside Thorn Eberhardt and Peter Elbling) was similar in several places to Alter's script. A jury eventually ruled in Alter's favor in 1993; with Disney having to pay $300,000 in damages.
in damages.