Back to the future rig up an old camera and show old home movies or just pretend and use Netflix or any one of many free online resources – keep them short and keep them laughing.
Old deck chairs are ideal – after all that is what they actually used in the old days of out theatres. Otherwise set your chairs up but remember to keep each row slightly offset so that each person gets a view of the screen.
There are lots of online sites such as https://free-classic-movies.com/ or http://classiccinema.org/ where you can livestream or download some great old classics – seriously Buster Keaton silent movies are hilarious,.
Plenty of pop-corn and cold drinks .