When the missiles launch, the count down goes from 19 down to 12, then 7, then back to 10.
When Dr. Gaskell, Vera and Arnie land on top of Kronos and are being irradiated by magnetic beams, Arnie is facing to his left in the frontal shots and to his right in the rear shots.
The truck being driven at the beginning of the movie, which was obviously filmed indoors, has no windshield, as evidenced by the sun visor partially extending into the opening. In the next scene filmed outdoors, the same truck now has a windshield.
When Les and Arnie are watching the telescope's view plate, they can clearly see an obvious spacecraft moving in a zig-zag pattern. They repeatedly refer to it as an "asteroid."
It is unexplained (ignored?) how Kronos had any forward motion with legs that just pounded up and down, something not physically possible.
Holy smokes! If Dr. Arnold Culver's figures are correct, "M47" is traveling at slightly greater than six million miles per hour ("seventeen hundred and fifty miles per second")! By comparison, the Earth is doddering about the sun at around sixty seven thousand miles an hour.
The close shots inside the helicopter, supposedly in flight, has a shadow of the blades which reveal that they are turning very slowly.
That asteroid M47 is a tricky devil. Not only did it zig-zag fifteen degrees before Dr. Gaskell's eyes, it also paused and rose at the beginning of the film when he wasn't watching.
When the Mexican Air Force planes attack Kronos, they are clearly shown to be P-51 Mustangs (with V-12 in-line engines) in the shots shown approaching the target. When the attack begins, they change to completely different types of aircraft with radial engines, probably F4F Wildcats or F6F Hellcats.
After the first nuke is dropped on Kronos, it is shown to have no damage, but there is also no damage to the surrounding landscape.
During the evacuation of LA, traffic is showing flowing both in and out of the city in roughly equal amounts.
In Arnie's first scene, he sees the security guard and another man carrying a body down the hall. When he goes into the room with Les, he makes no mention of it as if it was a common sight at Lab Central.
In the huge Science/Observatory complex, there hardly any people around except the main characters.
In most external shots of the helicopter the sound effect used is that of a propellor-driven fixed-wing aircraft, not a helicopter.
In one early shot of KRONOS's machine, when its main dome is flashing as the helicopter flies behind it, look closely at center of the flash and you will see a studio tech's hand opening and closing in front of a studio light illuminating the dome.
The one inside shot of Kronos's dome has a shiny metal cube in its center. On the cube's lower right corner, you can see an electrical toggle switch.
The target coordinates 27 14 52 North 175 18 07 West is not near Los Angeles, but is northwest of Hawaii near the Midway Islands.
What of the 4.9 mile wide saucer? Is it still out there in the ocean? After Kronos appears, no one ever bothers to inquire.