Electrocution!
In one scene, the kids are trying to fix up an old TV when it overheats and starts on fire. One kid reaches for his super soaker watergun, while another kid dumps a cooler over the blazing appliance. No one was injured.
Wow, I was shocked (figuratively) when I saw this! Had that been for real, that kid most likely would have been electrocuted. I wonder how many Japanese kids are now going to therefore think a bucket of water is the best way to extinguish an electrical fire when the kitchen toaster catches on fire...