Audio problem: When the boys are beating up Mikey during the flag football type game, he knees one of the kids in the crotch. An African American boy then says "man you should start wearing a cup." The boy's mouth doesn't match.
Audio problem: After Bobby says the "F" word, he says "someone get me soap, I'll do it myself." His mouth doesn't match.
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.