Can a mice eat a snake?

It's possible for mice to injure snacks, and that might include nibbling away at them.

There's been many cases of irresponsible keepers giving a small snake too large of a mouse and the mouse injuring the snake as a result. That's why dead rodents are much safer to feed to snakes. If the snake is finicky and refuses to eat pre-dead food (which does happen) then they should be supervised during feedings and small prey should be given. When using live feed, many snake keepers prefer to knock the feed animal unconscious before putting it into the enclosure.