When the van 'crashes', the aerial shot shows the skid-marks on the road that lead to its final position. Very dramatic - except they show a U-turn swerve that wasn't in the previous sequence of the van veering to one side and stopping.
After being told that they are only allowed to use the tranquilizer-firing rifles, the team don't carry them when they leave the building, instead sticking with the weapons they've been told not to use.
When Karl is being disparaging about being ordered to use AR-15s, the rifle he claims to prefer, carried over his shoulder, is a derivative of the AR-15. Meanwhile, the replacement 'AR-15' rifles they are given are Kalashnikov derivatives.
When Deacon arrives, he puts a magazine into his rifle (from what looks like an entrenching tool pouch) and slaps it home, before bringing the weapon to his shoulder and advancing. At no point does he actually cock the rifle to load it.
At no point does Karl ever seem to actually have a magazine in his rifle - even when firing at one of the dinosaurs. The muzzle flash and ejecting cartridges are purely CGI.