On occasion I'll get my gear wrong. Usually when down shifting more than one gear. The motor will rev up and my GF will ask "what was that?" I answer, "a mistake".
I paid attention the first couple of years. Then I got cocky and quit paying attention, and taking turns faster. The first time I took a left turn about 20 miles an hour, and downshifted into 1st from third when I thought I was shifting into 2nd I realized that was a big mistake. My rear wheel spun and broke loose and I went into a skid, that I somehow got out of. I think my *** puckering created a vacuum which pulled my wheel back in. So I either pay attention to what gear I am in, or release the clutch slowly in case I downshifted too fast.