The list is nearly endless. Cross threading the fixed cup on a bottom bracket. Putting in too few bearings in a hub. Putting in too many. Taking a freewheel apart. Forgetting to tighten a pedal (it fell out). Not torquing crank arm bolts. Not checking the brake alignment on my daughter's bike and not realizing it for ~2 years (no wonder she was always so slow
) Not tightening the stem on a bike tightly enough. Not tightening the brake levers enough. Not tightening the stem faceplate tight enough. Tightening the bolts on racks
too much. Twisting off bolts in anchor cables, brakes, stems, seatposts, etc. Using Phil Wood Tenacious oil for chain lubricant. Using any oil based lubricant for chain lubricant. Using too much chain lubricant. Mushrooming the cantilever brake mounts on a bike so that I couldn't take the brakes off for ~15 years. Pulling out the threads on a crank with a crank puller.
It goes on and on. The only difference between an inexperienced mechanic and a master mechanic is the number of parts they have ruined.