Re: How did Paul Hanlon got in and out of the stadium?
Yes! Unless he had a key to a back entrance or snuck in with a group or something, he would have to buy a ticket in order to enter the theater. The Magnolia was showing "High Plains Drifter" - a very popular movie that year. It's highly likely someone would have seen him entering the theater and it's likely he would have been seen sneaking into the projector's room.
Re: How did Paul Hanlon got in and out of the stadium?
Robert Culp characters on the show have a few things in common.
Even though one of them does it accidentally, two of them are blackmailers who kill their blackmail victims - "killing the golden goose" (as Jerry Parks would say).