Sadly just got back from our trip, so I finally have time to sit down and write out our review. We went to the 8/22 after hours. We also did the 8/19 AK after hours.
Both parks seemed to have similar crowd levels - both were very low. I was worried the MK event would have higher crowds because of Villains just ending, but it was a nice surprise that they were exactly as I expected. There were a few times towards the end of the night walking from Frontierland to Adventureland that we were the only people in sight. For the most part though, there were other people around.
We arrived right around 7pm and rode whatever we could pick up FPs for. At 10pm we made a snack break in Fantasyland and grabbed a mickey bar and a water. CMs were checking wristbands and told the person in front of us they aren't allowed to sell things either. Got to BTMRR at 10:10, walk on. We had to walk through the regular line. They were running both sides. We rode twice and then headed to Splash, which was also a walk on.
At 10:45, we were off Splash and made another snack break before circling back to Fantasyland. We did Peter Pan, which was a 2-3 minute wait. This was the only ride they were sending us through the FP queue. At 11 we did 7 Dwarves. Posted 10 minute wait, took about 7 minutes.
Continued circling over to Tomorrowland and did Speedway. Posted 5 minutes, we waited 10. Only 4 cars were being loaded so it got backed up. Seemed to stay backed up most of the night. At 11:30 we were at Buzz. We rode twice, and they let us stay on after the first ride. Space was down for a bit (maybe 30min-1 hour) at the start of the event. At 11:45 it was posted 20 minute wait, actually waited 10. Only one side running.
Took another snack break walking back around the park. Did the lantern photopass at 12:10, only one family in front of us. The line was pretty long earlier in the event, so I'd definitely wait until closer to to the end if you want to do this. Then we went back to Frontierland and did BTMRR twice more. We were allowed to stay on.
Took another snack break before heading to Pirates, which was a walk on. Jungle cruise was our last ride at 12:50, also a walk on. We then headed back to the castle and took photos at the front of the park. They did have photopass photographers stationed all along main street. We were out of the park by 1:15, and on the bus shortly after. The resort boat and monorail were not running, but the TTC ferry was. Contemporary, GF, and Poly all shared a bus.
We ended up with 4 snack breaks, and our ride counts:
4x BTMRR
2x Buzz
1x Splash
1x Peter Pan
1x Speedway
1x 7 Dwarves
1x Space
1x Pirates
1x Jungle Cruise
Overall we had a great time. For us, we'd only do the event again if we only had a day to spend in MK. We had already done 2 full park days there, so we had already accomplished everything we wanted to earlier in our trip. If you don't have that long in MK, I'd definitely recommend the event.
Editing to add a photo from Fantasyland. This was around 11pm, and what crowds looked like around most of the park.
