So, you build a beautiful house...

Mostly it's trash cans for the kitchen and outside, and the fire alarm - I forget that a lot. I once forgot to put a sink in the kitchen. One time I moved a chair I wanted to keep and set it in front of a desk without locking it in while I switched desks. I shifted views and it looked like the chair was there, but my sims wouldn't sit down. Finally I figured it out "Oh, so that's why you won't sit down at the computer!"

Sometimes while I am building or renovating I'll move a piece of furniture I'm considering keeping into a different room or outside while I'm shifting things inside. I left a TV in the middle of the porch in one of my DH remodels and had to quickly sell it in the few seconds before the clients got back for the reveal. The other day I found myself wondering where my sims had gone in my newest build. It was the middle of the night and they were all asleep in the beds I'd forgotten about in the back yard!