There's a movie from around the 80s I think that featured some high school project that went awry. It created rifts/portals to other worlds (or maybe just in time). I remember assault rifles, dinosaurs, and the characters maneuvering through the school (it may have been a mall, too?) hunting for something or other. Hell, it may not even have had any dinosaurs, but I kinda think it did. Sorta. Maybe.
Incredibly vague, I know, but I did a half-assed search for it not too long ago without any luck. Any idea what it might be? For some reason I have it associated with The Manhatten Project
in my head, but obviously that's not it.
EDIT: Once I gave up on the idea of dinosaurs, searching pulled up The Science Project
. That very well could have been it.
EDIT 2: Sweet, there are dinosaurs. This was it. (Hooray for thinking things out 'aloud'.)