Not sure if these are considered fun, but here are some tidbits I've found/observed:
On the air powered coaster, a flat, unbanked to banked track piece counts as a drop on the test results.
Of all of the campaign scenarios, A National Treasure is the only one that forbids tree removal. However, there are no pre-existing trees inside the park area or purchasable land, so the rule is a bit pointless unless the player decides to plant trees themselves. (The topiaries are not considered trees and can be removed normally.)
Although the background and landscape of The Money Pit strongly suggest the park is in a desert, the climate of that scenario is set to temperate, so it occasionally rains in the scenario.
All of the in-game water rides forbid children.
The galleon animatronic from the base game comes with supports. If you place the animatronic above ground, you can see the metal tiles underneath. In Captain Blackheart's Cove, if you remove the water body, you can see the scenario designers placed blocks under the galleons to kill the supports, so the ships look like they are naturally floating on the water. The newer scenery items don't seem to have this problem. For instance, the outrigger from the paradise island theme doesn't come with any supports, so you can directly place it on the water without all the hassle.
I've also had a lot of fun abusing my park staff:
Janitors don't seem to have an animation for falling. If you drop a janitor off a cliff, they strangely look like they are sprinting down the cliff.
When an animal keeper drowns, her shovel will levitate above the water next to her.
Janitors, security guards, entertainers and animal keepers seem to have the same animation for drowning, except the animation seems to play at a higher speed for janitors and animal keepers.
Excluding the park inspector, the staff don't have special animations for swimming inside a pool complex; they just drown instead of swimming normally. (The game doesn't let you directly place the staff inside a pool, but you can make a roller coaster explode near them and knock them into the pool.) The staff, however, are capable of rescuing themselves and leaving the pool (provided the pool complex has a changing room.)
And lastly:
The wooden benches in Vanilla Hills can fall apart. The strange thing is that I have never seen that happening in any other scenario, or to any other type of benches. I wonder if anyone has more information on how benches break in the game.
Good luck with your videos!