Goku starts out in the tenth anniversary special wearing the same gi he wore at the beginning of Dragon Ball (all blue.) But not long into the movie, he has switched into the outfit Kid Goku wears in Dragon Ball GT (blue top, tan pants.)
When the Red Ribbon Army opens fire in Suno's house, they destroy the "toilet" sign on the bathroom door. Yet in all subsequent scenes after Goku has defeated this division of the army, the sign is restored.
As King Piccolo is getting ready to make is wish, he pulls the five balls out of the ground that Roshi hid there. He brings them toward him and there are seven balls. Then he proceeds to take out of his mouth the two that he swallowed earlier.
One thing that seems to cause confusion amongst people posting goofs on the site is the status of the moon. People claim Master Roshi destroyed it in the original series but it was back in Z when Piccolo destroyed it. The original Dragon Ball briefly states, however, that Kami restored the moon himself.
When Goku beats Tien in the 23rd World Tournament, the announcer says Goku will go on to fight Piccolo Jr. in the finals. However, at this point the Shen/Piccolo Jr. fight had NOT yet taken place. Therefore the announcer couldn't have known this.