Most of my 'mishaps' involve the milling machine. I spend 90% of my time in the workshop running my lathe, and the mill can go weeks without being switched on, so when it does, there is inevitably some re-learning required.

My most common mistake is still typing G0 G53 X0 Z0, then standing wondering why the Y axis hasn't gone to machine zero
Which is often followed by zeroing the wrong offset...