Ok this movie I am not sure of the exact plot - it's a bit fuzzy. I think it was a couple guys, high school maybe? They were either in a gym or a museum, and they get stuck there - have to fight vietnam battles and I "think" dinosaurs. It reminds me of the plot of the new movie "a night at the museum. . . "

Anyone, help?

The only movie I can possibly think of that has ANYTHING to do with all that is House II.
It's an eighties movie... possibly not the same one... but all in all a still great movie.

It's a movie called my science project this review is from amazon.com

Amazon.com
Faced with not graduating unless he completes his science project, a high school gear-head sneaks into a nearby Air Force base, looking for some gizmo he can pass off as his own invention. What he finds is an alien energy device that rips holes in both time and space, infesting the school with everything from dinosaurs to the Viet Cong. Writer-director Jonathan Betuel tries to mine some of the same veins as Weird Science and Real Genius (all three films were released in 1985) but with less success--mostly due to a slapdash script. The film veers from being The Breakfast Club to WarGames to Rambo, leaping over plot holes all the way. As the hero, John Stockwell is too low-key for his own good, but Danielle Von Zerneck is appealing as his emerging love interest, and Fisher Stevens and Raphael Sbarge do their best to inject some life into the material. Dennis Hopper (as a hippie-dippie science teacher) chews the scenary with gusto--and at one point shows up wearing the costume he wore in Easy Rider. --Geof Miller