I'm self-taught and never competed, so my mishaps outnumber my successes. Honestly this may be the best way ever to learn something.
-split my pants in the bottom of the squat
-shit my pants in the bottom of the squat
-caught the "tip" on the way up in a clean
-locked out overhead, then dumped the bar, and THEN remembered I wasn't using bumper pads or anything...CLANG
-locked out a PR and then threw my back out unracking the weights, oh irony
-sprained a tendon in my knee trying to teach someone else proper form
I can keep going...I have made most of the non-lethal errors a newbie can make.