Corrected entry: The shark in the Motherfucker's tank never moves/swims. If a shark isn't constantly in motion, it dies. This would be fine if it was a fake shark, or always dead, but it turns out to be alive and kills one of the characters at the end.
Corrected entry: The blue truck is ridiculously close to the van. No driver in their right mind would drive that close behind someone (even the most obnoxious tailgater) on the freeway, let alone when there are people firing automatic assault rifles in there.
Corrected entry: When Mother Russia places the lawnmower on the back of the police car it continues to run, however that type of lawnmower needs the bar on the handle to be held down for the engine to run.
Correction: It's not true that sharks need to constantly swim or they die. Shark Week on Discovery seems to address this every year. While "modern" sharks generally breathe by flowing water through their gills while swimming, the majority of sharks can also breathe by pumping water over their gills through their mouths. Also, if there is a lower salinity, and higher oxygen content in the water, they don't need to swim as much to breathe.