When Peter and Clark are in Gotham to interview Bruce Wayne, Peter's fold-out bed flips back up while he's still in it, and he comments that it's actually less uncomfortable that way. Later, it happens to both of them at once, and Clark agrees.
When Leviathian first sees Namorita, he's so distracted by her beauty he walks into a wall.
In "Myxed Up" (Chapter 31, Part 3) Mxyzptlk begins to try to mess up with the people at the Xavier Mansion. However, as soon as people learn how to trip him into leaving (making him say his name backwards) it becomes hilarious. The high point is when he comes to Wolverine:
Logan:(after grabbing Mxyzptlk, tossing him into the wall and pinning him with his outer claws while making the middle one slid out) I don't know if I can hurt you, but I'd be happy to try. Now, I think you've got something you'd like to say. Mxyzptlk:Kltpzyxm!! KLTPZYXM!! Logan: Smart fella. (Mxyzptlk pops out)