One of my worst experiences at Disney was leaving MK at night during a spring break week (this was about 5 years ago). It wasn't so much the crowd surge at Main Street, but at the parking lot trams. We arrived at the tram lines that night around 11:15 or so. The Tram castmembers for some unknown reasons were holding up the departure for each tram by a good 5 - 10 minutes. When I looked up and down the trams, people were getting loaded very quickly and even folding up their strollers right away, so I don't know what the holdup was. Saw at least one fight almost break out when someone tried to jump the line. The whole crowd starting to clap and cheer sarcastically every time the tram would eventually take off.
We didn't get on a tram until 12:30 or 12:45am. Had we not parked in the very back of the Villains side of the lot, we would have walked. (in hindsight we would have walked but had no idea it was going to take that long - we weren't terribly deep in the lines when we started)
I don't know what the purpose of the CMs to hold up the tram loading process that night was, but it basically made us swear off staying off-site again. Not a good lasting impression to have when leaving the park.