When they bring wounded Anton to Geser's office and lay him on the table, Anton's face has just a few smears of blood. When they are done pulling him across the table, Anton has blood all over his face.
There is a shot of the damaged jetliner flying towards the vortex, viewed from behind. There are four distinct exhaust plumes from the four jet engines, despite the fact that one of the port engines was supposed to have been earlier destroyed by striking a crow.
When Anton and Olga are in Yegor's apartment explaining the vampires to Yegor, Anton is watching the news on TV. When he moves to the smaller TV and turns on the news, it says "MUTE" on the screen, but you can still hear the news anchor talking.
Near the end of the movie, during the rooftop scene amids the dark vortex, Anton wields a long fluorescent light bulb as both a lamp and a sword. The glow that is visible from the bulb is clearly not a special effect - the play of shadows as the bulb moves is far too accurate. But if the bulb is actually lit, then there must be a power supply somewhere. If the viewer watches closely while Anton is swinging the bulb about, a wire can be seen coming out of his sleeve, to be obscured behind the bulb. It should be noted that there is never a single, continuous shot showing the entire circumference of the bulb. This is most likely because the wire front Anton's sleeve runs along the "back" of the bulb to supply the necessary power.
In the international cut, when Anton reads his profile, he learns that Yegor is his son. But, just before, the profile reads in Russian (although Anton doesn't spell it): "Children: a son", and Anton doesn't seem to notice (this is due to the fact that in the original cut he already knew it).
The Second time we see Yegor watching 'Buffy' on TV the shot shows one scene as he stops in front of the TV. He then turns and the reverse shot shows a different scene on the TV but the audio has continued from the original scene, a lot earlier in the episode.