I installed a tub surround, and when I cut the holes for the fixtures I messed up on the hole for the tub spout. When the spout is attached I have a 3/4" hole to the right of the spout that I need to cover up. Is there some sort of plate I can use to cover it up?

There are all kinds of adapter plates and escutcheon plates at HD and Lowe's. Check in plumbing near the faucet repair area. If nothing fits, get a small piece of Aluminum, cut a circle, cut a hole for the pipe and lightly sand it to look like brushed nickel. Then, sand the tub area and epoxy or silicone in place. Have done this many times when refitting faucets.

Epoxy works great.

If you can get to it from behind, see if you can move the spout to the side. That would be the perfect fix for your situation - provided the hole size fill "fit" under spout end.

Also, I like the ma0641 advice.

Hope that helps

Milo