John Mazzello, the younger brother of Joseph Mazzello, appears as a school boy extra. Hannah Wood, the younger sister of Elijah Wood, appears as a school girl extra.
Writer David Mickey Evans has stated that the script was much darker than the final film, and the child abuse angle was more prominent. When the film was taken over by Richard Donner, those elements were toned down. He also felt that the studio marketing "Radio Flyer" as a family film was a factor for the film's failure at the box-office.
The original script called for more fantasy sequences involving a worm man and zombies. These ideas were scrapped when Richard Donner replaced David Mickey Evans as the director.
When Mike is reading the postcard from Bobby (at 105:19), you see that their last name is Wright - as in the "Wright Brothers". Also, the envelope from Magic Spell, Inc., (at around 54 mins) is addressed to "Mike and Bobby Wright".