The voice of Brain, during the credits, was the voice of the animated Inspector Gadget.

In the beginning of the credits, you see Claw's evil henchman in a Minion Recovery group. Many of the other people in his group are former James Bond enemies.

In the scene where Gadgetmobile first meets Inspector Gadget, he says something about him making moves on Dr. Bradford. Inspector Gadget says his only interest in her is professional. He says the same thing about the female Inspector in Inspector Gadget 2.

When evil Gadget is doing the shadow, it's actually a mimic of the Lost World, most easily noted by the Japanese salesman being translated I left Tokyo to get away from this. However, in The Lost World it was not translated, and filmmakers thought a line that good should be recognized.

I wouldn't want to stay at the hospital that Gadget was staying at. When Penny runs into the room with the man in the body cast, someone on the intercom is saying 'Paging Dr. Howard, Dr. Fine, Dr. Howard. Paging Dr. Howard, Dr. Fine, Dr. Howard.' The Three Stooges were Curly Howard, Larry Fine and Moe Howard.