In Eegah's cave, Roxi gives Mr. Miller's face a shave and finishes before Eegah returns. But once Eegah actually returns to the cave, we see Mr. Miller's face still completely covered in shaving cream and Roxi is just starting to shave his face.
In close-ups, the helicopter pilot has rather bushy hair, but in the long shot, when he's landing the helicopter, he has a crew cut.
When Eegah is trying to rape Roxy outside the cave, he tears both shoulder straps off her dress. When the scene shifts from close-up to a medium shot, Roxy's left shoulder strap is fastened.
In the scene by the pool, an actress who has 'swooned' is lying near a post. When the camera returns to the scene, she has moved to a different spot in relation to the post.
In the final monologue, the Robert Miller character says, "Yes, he was real. It says so in the Bible. There were giants in those days - Genesis, Verse 4, Chapter 32." The correct passage is Genesis 6:4. "There were giants in the earth in those days; and also after that, when the sons of God came in unto the daughters of men, and they bare children to them, the same became mighty men which were of old, men of renown."
At the end, Robert Miller (played by Arch Hall Sr.) quotes the Book of Genesis, Chapter 4, Verse 32: "There were giants in the Earth, in those days." That verse doesn't exist; in fact, there is no verse 32 (the quote is from Genesis 6:4, not 4:32).
When Mr. Miller and Kruger first search for Eegah in the helicopter the moving rotor blades are reflected in or around the helicopter from most camera angles, eg on the instrument panel. However, on an external shot from the pilot's side of the helicopter, no reflection can be seen anywhere including the canopy, indicating that this angle was shot on the ground with a stationary helicopter.
On the first title, the last 3 letters of EEGAH are dripping blood, however, no blood is shed in the film.
After his shave Arch Sr looks clean shaven. But after Eegah gets his shave, the next shot of Arch Sr shows him with a stubble.
After Eegah is first discovered, Roxy's father begins to walk off screen but yells "Watch out for snakes" without his lips moving.
Tom's band is obviously miming during the last instrumental that they play.
When Tom is singing in the band by the pool, his voice is amplified and projected, but he is not singing into a microphone.
When Tom fires his gun into the air and at Eegah, the gun he is holding is a double barreled shotgun, but the sound is from a .22 rifle.
At the start of the film when Roxy is driving her sports car, the sound of the engine does not match the car's movements.
The heavily lit night scene in the hotel parking lot reveals many reflections of lights, equipment, crew etc. in room and car windows (especially the police car).
When the dune buggy turns in front of the camera, the shadow of a crewmember falls on the ground and part of the dune buggy.
In one scene in the canyon you can see the shadow of the crane, the camera operator and the camera - the works - accidentally projected on a rock wall.
When Eegah lopes from his desert cave into modern town civilization (to search for his new amour Roxy) he's fascinated / confused by the untouchable manikins behind supposedly unknown to him glass .. but as soon as moves on to cross nighttime's road, he quickly checks both ways, presumably to be assured it is clear of modern dangerous cars ... (well, he was almost run over by Roxy in the opening reel, so perhaps he just learns quickly!)