film enhancements

Any others Im missing? - Gimmicks, weird things that happen in the theatre - etc

The Tingler (1959), filmed in "Percepto". The title character is a creature that attaches itself to the human spinal cord. It is activated by fright and can only be destroyed by screaming. Castle purchased military surplus airplane wing de-icers (consisting of vibrating motors) and had a crew travel from theatre to theatre, attaching them to the undersides of some of the seats (in that era, a movie did not necessarily open on the same night nationwide). In the finale, one of the creatures is said to have gotten loose in the movie theater itself. The buzzers were activated as the film's star, Vincent Price, warned the audience to "scream—scream for your lives!"[7]: 17  Some sources incorrectly state the seats were wired to give electrical jolts. Filmmaker and Castle fan John Waters recounted in Spine Tingler! how, as a youngster, he searched for a seat that had been wired to enjoy the full effect.

Of course all the Rocky Horror stuff

Odorama (scratch-and-sniff cards handed out to the audience - also included with the DVD releases!) for "Polyester": https://en.wikipedia.org/wiki/Polyester_(film)#Odorama
I didn't know this until just now, reading that Wikipedia entry, but apparently Waters was influenced by another Castle film gimmick, Smell-O-Vision used in "Scent of Mystery."

Good! I guess 3-D specs also.

Idk if it was actually implemented at any point but I remember reading that they were experimenting with smell-o-vision technology for Malick's The New World, perfume-filled globes (or something) throughout the theater that released scents at different moments in the film

Smell is definitely an under-appreciated element in film. However you woul dhave to be careful to venture too far - smells can ruin an experience