Once on my wife's Subaru Outback, the oil filter gasket from the old filter stuck to the housing and on the initial startup blew out and dumped the oil all over the driveway while I sat in the car and let it run. Shock when the oil light came on, shut the car off and got out to a huge mess.
Haven't done it recently, but there have been many times over the years I forgot to replace the drainplug in a diff or transmission or engine.....
