Continuity mistake: In the first scene with Bobby's first postcard, he writes his name as "doddy" as a young child might, reversing the Bs. Later, when you see the postcard hanging by a string, it is written "bobby" instead. (01:44:55)
Continuity mistake: When the family moves into the new house, the father rips the former owners' name sign off the front of the house. A few shots later, it's back.
Continuity mistake: As the boys are running through the sewer tunnel, both of them fall several times, and they are covered with dirt and sewage. When they come out and face the bullies, their clothes are clean.
Continuity mistake: At the end when Mike receives the first postcard from Bobby, the flag on the mailbox is up, meaning there is mail to be picked up by the postman. Then when he takes the mail out and runs towards the house, the flag is down without him touching it.
Answer: The script's ending was ultimately changed by director Richard Donner from what writer David Evans had originally written. In the original ending, it was made clear that the Radio Flyer had actually worked and it was seen hanging (actually floating) next to the Wright Brother's plane in the Smithsonian. Donner instead wanted the ending to be a "Rorschach Test", meaning the viewer sees the ending as he or she wants. So if you perceive it as working and Bobby being free or you see it as Bobby committing suicide, etc, it's meant as a reflection on you. However, Evans has said that he never intended the ending to be, or allude to, suicide, but because of the script changes, he understands how people could make that conclusion.
Bishop73
I have watched this movie 3x in the last 2 days. It has emotionally exhausting and I have done more research on this film, the actors, the original intent for the films direction by David, I mean you would think I'm nuts! But after paying close attention, 28min into the movie, the boys discuss exploring the hill where Fisher jumped off one day. The look and sound of Bobby's voice when he said "he died, no-one can make that jump" is what leads me to believe he was telling us the viewers.
His fate. I think Mike tried to help him, and describes the idea as a "dangerous" one. In their attempt to fly, things of course go wrong and Bobby dies during the crash. However mike in his young mind, created the story of Bobby actually getting away. A grown up mike seems sad, depressed and a little off. He still struggles with his trauma.