Mousey startled Blue and made his telekinesis on Goku wear out giving Goku the upper hand again. After Krillin and Bulma go ahead of Goku while he gets the Dragon Ball, he stops to save Mousey and runs off with him in his mouth, intending to repay him for his involvement in saving him. When they reached the surface again and ended up at General Blue's Camp, they let Mousey go.
Video game appearances
Mousey appears as an item that stuns General Blue for one turn when used in Dragon Ball 3: Gokuden.