Revealing mistake: The "Old man-ghoul" changes appearances drastically throughout the entire movie. In some scenes, it is Bela Lugosi in vampire cape, in others it is the famous "double" who is a head taller than Lugosi, a lot thinner and has a different hairstyle. He covers his face with his cape, but this does not help a lot...Twotall
Visible crew/equipment: While the spaceship is flying, the string is very visible. Also, you can see on the bottom of the spaceship/plate that there is a flowery design. (00:04:45)
Continuity mistake: When the flying saucer is seen taking off from the cemetery, it is saucer shaped. However, when it is on the ground the ship appears to be in the shape of a square building. (00:37:05)
Plot hole: Eros makes it very clear that his race does not 'cling to life.' If this is the case, then why is he so determined to save everybody?