The first time Morgan goes searching for corpses to incinerate, he puts a man and a woman into the back of his station wagon head first. When he arrives at the garbage dump, the woman is now lying feet first in the back of the car and has switched sides with the man.
In the flashback sequence where Morgan takes his wife's body in his car for a secret burial, the shots of him inside the car driving shows that it is night or pre-dawn. However, the exterior shots of the car moving along on the road show that it is already daylight.
During the flashback, when Robert returns home from the lab he pulls into the driveway and the steering wheel is on the left side. He exits the car the on the right with the steering wheel on the right side as well. When it cuts back to the wide shot the steering wheel is again on the left.
When, at the dump for the first time, he carries the woman to the edge of the pit, her head is on his left arm. When the shot changes from a long shot to a close up, she has shifted 180° and her head is now on his right arm.
While looking at the newspaper clipping in a flashback, the headline reads, "PLAGUE CLAIMS HUNDREDS Is Europes' disease carried on the wind?" The word "Europes'" (with an apostrophe and plural) is incorrect. It should be only possessive and singular, "Europe's", as there is of course, only one Europe.
The newspaper headline has an apostrophe typo: "Is Europes' disease carried on the wind?" However, given the other typos ("wild fire" for either "wildfire" or "wild-fire" and "to day" for "today") the paper is clearly not very thorough in its proof-reading.
When Morgan returns home at night and is fighting the vampires he opens his unlocked front door and enters. The marauding vampires should have been able to enter the home, before his arrival, with the door unlocked.
Vampires, which they seem to be - killed by stakes, repelled by garlic, only coming out after dark etc - are not afraid of mirrors, they just don't reflect in them. Vincent Price's character users a mirror to repel the marauders outside his house and we see one clearly reflected And if indeed mirrors did repel these marauders then the one on the front door would have an effect, which it clearly doesn't. And neither does the garlic..
At the beginning, when Morgan goes out searching for corpses to incinerate, after he puts a man and a woman into the back of his car, it is possible to see the two actors moving themselves to settle down in the back of the car.