Factual error: In the scene where Bobby and Mike go into the comic book store, you can clearly see a Transformers comic on the shelf. But the movie is set in the late 1960's/early 1970's....and Transformers did not come out until the 1980's.
Factual error: The walkie-talkies the kids use at the end of the film would not make the squealing noise they do. The walkie-talkies they have transmit on high enough frequencies that this would not happen. Mediumwave and Shortwave have this effect, not walkie-talkies.
manthabeat
Answer: Yes. He actually did fly off. Adult Mike even tells his two sons that sometime after Bobby flew off, he began receiving postcards from Bobby from every place he traveled to and still keeps sending postcards to him.