I installed the mudguard myself and I noticed I didnt align the rear mudguard correctly, so there is a noticeable gap. I drilled the holes a little too low. Is there some kinda of sealant I can use to plug up the screw holes so I can make new holes for better installation.

 

The rear guards have little metal clips, right? If so, things will probably stay in place even with a bad hole. If not, you're going to have a hard time patching that, assuming you have to drill right next to it... sorry. There is a chance that whatever piece you drill into is replaceable, but I'm not sure how big it is.