Some of the ones I can think of immediately are:

Scary Halloween masks
Any immediate loud noise that sounds like a gunshot sets me off, I bawl like a baby.
Caffeine (I just tell people I am allergic, it's easier)
Elevators
Groups of people/crowds (I feel like I am trapped and I can't breathe)
Hospitals (the smell reminds me of the times I was inpatient for MH issues/ED)
Airplanes
Car trips if I am not the one driving
Weird pains in my body (I start thinking it's my heart, or my appendix, or something terrible but I am not a hypochondriac, I just think something bad is gonna happen...)
Pools (because of the whole bathing suit thing...so exposed!)
Family gatherings
Getting yelled at or even people yelling in general (doesn't have to be at me)

I am sure there is more, but I don't want to have a list a foot long...