Big/Trivia

Hey, It's That Guy!: Kitty Forman is Miss Patterson, Josh's secretary.
The Other Marty: Invoked during filming. Reportedly, Penny Marshall had David Moscow perform scenes of the grown-up Josh to help Tom Hanks get a handle on a how a kid would behave in an adult setting.
The Red Stapler: Since its first release, many people have stopped by the FAO Schwartz on Fifth Avenue to play the floor keyboard.
Throw It In: The scene where Josh and Billy shoot Silly String at each other was derived from Hanks, Rushton and Moscow being left in a room filled with toys.
Tom Hanks Syndrome: This movie marks Tom Hanks' transition from a comedic actor to a dramatic actor, even though the movie was part comedy, part drama.
What Could Have Been: Robert De Niro and Harrison Ford were considered to star as Josh when he becomes an adult. Also, Debra Winger was offered the role of Susan, but she turned it down because she was pregnant at the time. She even recommended Elizabeth Perkins for the part.
- Steven Spielberg considered directing the film (his sister co-wrote it, after all) but declined as his son had been born and felt he should be closer to him.
- The film was originally supposed to end with Josh back in school and meeting a girl named Susan -- who turns out to be the same Susan Josh met in his time as an adult, and made a wish on the Zoltar machine to become a kid again. This was rejected by test audiences and replaced with the ending where Susan watches as Josh turns back into a kid and walks out of her life.