The forgotten drain cap/ hose fitting issue made me think of some other things that have happened, so I thought I'd see if anyone had any stories they would share.
I remember we were having a huge weekend sale many years ago and we had just remodeled the spa department. Painted ceiliing, slat wall w/ glass block , new carpet etc ( sound familiar Watkins folks?) Anyway... big sale starts Friday morning. I decide to fill a Hot Spot at the last minute. Put the hose in, ask the rep to watch it, and next thing I hear is the rep freaking out cuz the water is pouring out the motor compartment. When I opened up the motor door, I found an entire section of piping missing. Turns out one of the service guys came by months earlier and "borrowed" it to fix one in the field but didnt remember to replace it or tell anyone.
I can tell you, there is nothing like having the store owner walk in after spending several thousand dollars to remodel and "squish" across the new carpeting and ask "What the *%$^ happened here?"