Not the biggest, but pretty big to me...
The cast sign-off just before credits rolled in TUC.
The movie was already wrapping up with a final farewell in Kirk's last log entry, already an emotional good-bye.
After the Enterprise sailed off into the sunset, I was expecting the usual "roll credits" ending.
Seeing that unexpected and glorious good-bye from the cast really got to me.
Being on old fart from TOS early days, these folks had been a part of, well, my whole life. That last good-bye to them brought tears.