Continuity mistake: Vada loses the right handlebar streamer in the garage, but later in the movie it's the left streamer that is missing. At the very end we see that she has both streamers. (00:35:15 - 01:16:25)
Continuity mistake: In the scene where Thomas J. pulls the fish out of the water, the hook falls out of the fish's mouth twice.
Chosen answer: Most likely because there was no reason for a scene of them together to tell the story. It is assumed that because Thomas and Vada are friends, that Harry has interacted with Thomas many times before. There could have been scenes filmed with the two actors together that was later cut from the final film. This often happens to quicken the film's pace, shorten the running time, etc.
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