WTH: National Treasure

I can't be the only one who's noticed this. So if you've seen the National Treasure movie you would remember the scene where you watch Ben and Riley preparing to steal the Declaration of Independence. They have this whole elaborate plot to make the document accessable by getting it moved to the preservation room instead of the high security vault that is technically impossible to break in to. Well at the same time this rival treasure hunter guy is also plotting to steal it. Pretty sound so far right? well when Ben is in the preservation room unbolting the Declaration display case the bad guys show up and start shooting at him.

Have you spotted the problem yet?

These guys show up at the preservation room to steal the Declaration, only no one knew that it had been moved there, Riley and Ben had only gotten it moved that afternoon, so how did those guys know where to go? Since they obviously couldn't have known the Declaration was moved then their plan must have been to storm the vault, something they would have needed more than just the small explosives they were carrying to accomplish, and how did they plan to escape hmm?

This plot hole is big enough to drive their escape van through, not to mention that for some reason, even though the bad guys only ever have like 25% or less of a clue Ben and his group can barely stay one step ahead. Yeah, the British must not have been very bright if they couldn't find the treasure, just saying.