I used to wonder why rockets were launched to the moon during the day when the moon was only around at night. Eventually I figured it out -- rockets weren't instantaneous, so by the time they got to the moon it would be night time.
There was another impressive logical leap after this, but I don't remember it. Probably for the best...
A childhood belief about physics

others believed things like this
- i used to think that the moon would follow you in the car, also that it looked like a half moon.— natalie k
- I used to believe that Moon is the kid of Sun, because it has less light and Moon smiles with kids. — Syed Arbab Ahmed
- I used to wonder that if man wanted to reach the stars in rockets, why didn't he just go up at night? Duh!!!— albinoavenger
- i used to think the moon followed me because i could always see it at nightAnon
- i used to believe the moon was following our car while driving at night.— pixie
- I used to think when I was traveling at night the moon followed me!— Joan Escobar