It is possible it were the tourist helicopters. There is a company on 192 that has red, white &black helicopters that does fly over Disney. Last April my family did this 20 minute tour. (It is actually quite interesting to see all of Disney from that view).
When we there this past February (during the heightened security level) that same company still had their different copters flying over the parks all day long. So, they must have some sort of permission to fly over Disney's no fly zone. Also, the same time we were their in February (with the media making a huge issue out of no fly zones and security level being raised), the goodyear blimp hoevered overhead for hours the one day. We assumed it was on it's way to the Daytona 500 (same week). However, it wasn't very high up and had to be in the no fly zone.
I do not think helicopter security at night would require 3 choppers and I don't know how much good it would do. I would believe that MJ would however would watch the show from them.