Most of Mel Brooks' films seem to be open matte as well. The trailer for High Anxiety is full frame and crew shadows can be seen in one shot. The number of open matte films with things that were never meant to be seen is probably huge. Here are a couple I recall from seeing movies one time too many on HBO back in the day.
The Jerk. Microphone visible on the bed below Steve Martin and Bernadette Peters.
Bachelor Party. As a character dangling from bedsheets falls, two stagehands grab the actor from below!
Pee Wee's Big Adventure. The endless bicycle chain gag is ruined, as you can see it's being fed from underneath.
The Shining. The infamous helicopter shadow during the opening scenes.
IIRC, early video transfers of The Muppet Movie reveal a little too much below the waists of Kermit and the gang. The later films were either zoomed in to prevent this on video, or were shot hard matted.
Manhattan has the distinction of being one of the few films never shown in pan and scan on any video format. (I even saw it once on a UHF station with the gray letterbox bars in the late '80's.) The only other one I know of is Joe Dante's Innerspace.
There are a small handful of films squeezed slightly on older video transfers that can properly fill a 16:9 tv with the proper setting today.