(at around 27 mins) When Michael is at the pub and is being chased by the police, he jumps onto a police car and leaves a rather large dent. A moment later when he runs into the woods, there is a shot of the car and the dent is gone.
(at around 33 mins) During the fight on the truck, the vehicle is severely damaged, most notably on the passenger side when Marcus is crushed between it and the cliff face. Upon arriving at the warehouse, however, there is almost no damage whatsoever.
(at around 1h 35 mins) At the end of the film, sunlight is shining straight down through a hole in the cavern ceiling, indicating that the sun is directly overhead (ie, it is noon). But in an exterior shot, it is dawn and the sun has barely cleared the horizon.
(at around 31 mins) When Michael and Selene are running away from Marcus, you can see Michael standing on the road wearing a jacket, when he turns while stopping the truck, the jacket is gone.
(at around 47 mins) When Michael fights the guard wolf outside where Selene falls through the trap door, the car is damaged in the fight but it appears to be fine when they drive away.
During several scenes in the fortress, Selene empties her guns. After her pistols are empty the slides lock back but you can still hear click, click, click. That would be impossible as when the slide locks back you can't pull the trigger. The same happens when she empties her rifle and the bolt locks back.
(at around 1h 30 mins) Marcus brings down a helicopter by pulling on the attached cable. This is implausible and physically impossible. Regardless of one's sheer strength, unless he is anchored to the ground, the helicopter would have lifted him rather than get pulled down.
(at around 44 mins) The signs on Tanis's gate do not translate well because they are intentionally garbling multiple languages to keep from pinpointing the location of the film. Basically, the signs say a variation of "guard dog" in mainly Hungarian and Esperanto. (Esperanto was an academic attempt at creating a universal language that could be easily learned by anyone, and wouldn't have the imperialist baggage of English, French, Spanish, Japanese, etc.)
(at around 1h 17 mins) When Marcus is entering the area after the movable wall unlocked with the key, where William's prison is, you can see a hole in the ceiling where light is entering the room. There would no purpose for a unmovable wall if you could enter the room through a hole in the ceiling.
(at around 24 mins) During the pub scene the newscaster woman and the two soldiers speaks Hungarian in a foreign accent - not to mention the grammatical errors and mis-spelled words - revealing that they are not Hungarians but foreigners who can speak the language. When Michael enters the pub the background newscaster speaks the correct language.
(at around 1h 28 mins) Near the end of the movie, when Selene blows a hole in the ceiling of the cave, some of the rocks that fall down float after splashing into the water.
(at around 1h 30 mins) The Bell 412 Helicopter (Huey) is depicted with the main rotor spinning clockwise in the slow-mo crash scene. All US helicopters have main rotors that spin counter-clockwise when viewed from above.
(at around 23 mins) The coordinates shown for the "safe house" (Location 254, Long 32 12 23, Lat 60 21 44) link to a location in Iran (near to the Afghanistan border) while the movie takes place in Hungary (recognizable from signs as the one saying "Hazorzo kutya" when entering Tanis' hiding place).
(at around 23 mins) I am not sure if that image says 60 or 68 degrees, but it does say Lat so,...Lat. 68.21, Long. 32.12 is in the Murmansk Oblast of Russia North of the Arctic Circle and East of Finland...Lat 60.21, Long. 32.12 is near Leningrad, which is close to St Petersburg and the Gulf of Finland.
(at around 13 mins) Marcus kills violently immediately upon being awoken. This makes no sense in the context of the previous film, where awakening is shown to be a formal ceremony that is expected by the sleeping elders, and they awaken in a weakened state, desiring to know what has happened in their absence, not wanting to destroy their own coven who woke them.
(at around 1h 15 mins) Alexander Corvinus is immortal, but is shown killing himself using a powerful yet relatively small and simple bomb. He is at least 1600 years old: during the course of that time it is almost inevitable that he would have found himself in or near an explosion, be it natural or manmade. If all it took to destroy him was an explosion, he should have been killed long before the modern setting of this film. Furthermore, he appears to be dying from being stabbed by a sword and losing a lot of blood. A flesh wound and resulting blood loss during 1600 years would be even more inevitable than an explosion. No explanation is given for this, as he shows no healing abilities or attempt to use them. Again, if his immortality is based solely upon his body never dying, and not upon being invincible or having regenerative powers, then he should not have survived 1600+ years.