So Ive seen a lot of others having a similar issue, being that the game gets an error after trying to use act on the Water Cooler after finishing the fight part. If theres a way to fix this I'd appreciate it, same with the other people who are having the same issue as me.

Also another question, theres this large covered thing at the end of the maze. It shakes but Im unsure what it does.

I think the large shaking thing is just something for future content. I think it's Underfell Frisk hiding under there, seeing as he ran through the door leading back to the maze.