Factual error: The weapon Xander fires in the basement to kill the sniper with the might of his irony does not make sense (as noted before, it is non-existent and its prop is a modified camcorder). First of all, he is firing it with his back to the wall, and the deflected backblast alone would fry Vin Diesel's arse. Second; it fires a heat-seeking rocket that targets a single lit cigarette completely outside of Xander's range, to the point that the projectile does almost a U turn (way more than 90°); if it just goes for any smallest object wildly off the supposed target range (Vin Diesel is looking at a screen when he points it), then it could end up targeting the launcher itself, heated up by just having fired, or weapons or shells just fired by allies, making it useless in combat. Third; the screen Vin Diesel is looking at...is switched off. (01:38:40)
Factual error: There are no mountains high enough near Prague. The closest mountains that fit the description are the Alps between Germany and Italy.
Answer: Xander and Shaver were back at the compound where they first met. The one where Xander finds out that Shaver is responsible for making the gun and darts that were used to knock him out. In that scene Shaver shows Xander some of the cool stuff that he had made, and Xander uses a few items later in the movie.
Rollin Garcia Jr