It cannot be overemphasized how remarkable it is that the time travel story element doesn’t effect the ride in any meaningful way. It’s set up with laborious exposition in the pre-show. It’s highlighted by THE NAME OF THE ATTRACTION. And it could all be removed without effecting the ride at all. The pre-show might as well be Glen Close announcing, “The time-travel stuff was cut for budget reasons” - that’s largely the current subtext.
There are tons of ways to improve the pre-show. The most obvious is much better, tighter writing. Get an actor more adept at verbal buffoonery, like, oh, John C Reilly. I like Crews, but the part doesn’t fit him. Include something of strong visual interest rather then a series of TV screens - a giant, 3 dimensional Milano with AA Groot and Rocket, for instance.
On the most basic level, cut all the Xandar nonsense. EPCOT has a new Big Bang pavilion. As you walk through, you find it has been amusingly defaced by the Guardians. Now the queue serves a clearer story purpose - the mischievous Guardians are here and are dissatisfied with the new ride. In the one pre-show theater, the Milano has crashed into the room. Star Lord explains he loves EPCOT, but he can do it better - Rocket has rigged up a way to take guests back to the real Big Bang, although he hasn’t worked out all the bugs. Then make sure the ride has some cool sfx invoking the Bang, which are lacking now. Shorter, clearer, and the Guardians are both more central and more like thier film versions.