Around 40 minutes into the movie when the guards and Vince are inspecting Cyrus' prison cell; just after Vince reads out "Meet Cars", the camera zooms out and you can see the box in which Cyrus has hidden the bomb on the ground.

About 1 minute later when Vince realises it says "Meet Carson City" he gets up and leaves just after telling the guards not to touch anything.

One of the guards sits on the bed and picks up the bomb box off of the bed when it was actually on the ground.

It's also a bit hard to see but it doesn't look as though any of the plans and folders are still on the bed from when Vince was sitting there.