Many years ago (in the 1980s, probably), I saw some of a movie on television. I'm not sure if it was a feature movie or a made-for-TV special, and I never knew the name (this was back when you had to use the TV guide to figure out what you'd just seen).

It was about a little boy who traveled back in time (not sure why - missed that part of the movie). There were two memorable scenes in it.

The boy wanted to buy a chocolate bar, so he dug in his pocket and came up with a single dollar. He asked the store clerk if that would be enough, and the man told him it was more than enough, giving him lots of change. Later on, the man looked at the bill closely and realized it was 'funny money' - since it was a modern bill.

Later, the boy stopped for directions at a gas station, but the clerk there couldn't help him. Despite being treated rudely, the little boy stopped when he saw that the gas station price sign must have lost a number, since it only showed ~30 cents a gallon or so. The boy put up the 'missing' $1 in front of it, which caused the gas station attendant to wonder why so many cars were pulling up to the gas station, seeing the price, and zooming away.

Does anybody have any idea movie I'm talking about?