Established by many reviewers (including director George A. Romero himself) as a graphic blueprint for La noche de los muertos (1968).
The strange, tall, UFO or mushroomed shaped building in the background behind Dr. Robert Morgan is the "Ristorante Il Fungo" in Rome, built in 1957. It was restored in 2013-14. It is also featured in El eclipse (1962).
To more accurately show how grueling it was for his character to survive, Vincent Price insisted on lifting real people into the back of his car instead of dummies. This is why it seems he's taking extra care with the bodies. For the scene at the pit, however, he's handling dummies for obvious reasons.
Vincent Price admitted in later years, to having a fondness for the movie and rated it as superior to La última esperanza (1971).
Despite being regarded as the most faithful version to the novel, there are some noticeable differences. For example it depicts the vampires as slow-moving and uncoordinated. In the novel, the vampires were fast and agile.