Regarding wait times at the end of the night:
It is standard to inflate the "official" wait time, but this is even more true during the last 60 minutes before closing... particularly on major rides like Space Mountain. When necessary, CMs will even hold the lines so they visually appear to be longer than actual. This is done to discourage too many people from jumping into lines after closing, and the amount of the inflation may vary from night to night depending on judgment calls. If you actually do get in line before closing, you will be allowed to ride as long as the attraction is operating. I realize some people don't like the idea of artificially inflating wait times, but this practice has been in place for decades and is standard across the theme park industry.
That said, I have no reason to doubt the anecdotal accounts of people saying how crowded it has been at 10:00pm.