Day changes to night and back and forth in the same scene, many times. (Ignoring such changes is key to trying to make any sense of these sequences.)
When Jeff calls Paula from the plane to see if she's okay, a picture over the bed behind her changes from a landscape to a portrait of a man and a woman. The picture is normal at 30:35, then changes to the portrait at 30:47. It then changes back to the original picture at 31:04. It should be noted that this change only happens in the colorized version of the movie, the B&W copy has no such change.
When the police cars set out for the graveyard, it is broad daylight. When they arrive, supposedly a few moments later, it is pitch black.
Paula runs past the same spot on the cemetery seven times while being chased by "The Ghoul Man". "The Ghoul Man", on the other hand, only passes the spot once, but manages to make a headstone sway distinctly while doing so. However, he passes another spot on the graveyard (i. e. they've rearranged the headstones) four or five times.
When the Ghoul Woman attacks the two gravediggers, they are standing in broad daylight, but in the shot that shows her attacking them, she is in the middle of a pitch-black night.
On the airplane, co-pilot Danny is talking to Burbank tower, when Danny sees a flying saucer. Burbank tower asks if he is in trouble, and Danny responds: "Mayday, Mayday! Stand by, Burbank tower." The term "Mayday" is only used to signal a life-threatening emergency, and no real pilot would use it for any other reason.
The stars on the general's left epaulet are spaced much wider than the right. They should be, pardon the pun, uniform.
The pilot sitting on the left in the cockpit scenes calls the air traffic control tower using an Army T-26 chest-mounted microphone. This would not be used on an airliner. A handheld mike would have been used.
The pilots fly a Douglas DC-6B or DC-7, but the cockpit shots never show the flight engineer, a third flight crew member who sat behind the pilots and manned the engine controls.
Police officers are generally trained in how to properly handle firearms - yet in several scenes they are seen to grossly mishandle them, such as using the barrels of their pistols to adjust their hats, scratch the sides of their heads and gesture at others, all while their fingers are clearly on the triggers. It's a joke which the actors played on Edward D. Wood Jr.
The aliens are frustrated that the Earth people refuse to acknowledge their existence, yet go to extreme lengths to remain secret, such as killing witnesses. It is likely that they don't want to be discovered just yet; they want to build a complete zombie army first.
Colonel Edwards is in charge of a government division created specifically for dealing with flying saucers, yet during their meeting, Gen. Roberts insinuates that Edwards could be in trouble for acknowledging that the saucers exist, due to a government directive stating that saucers don't exist. Roberts is speaking rhetorically; outside of their privileged circle, "saucers don't exist" is the official doctrine fed to the public.
The Pentagon has a special computer to translate alien language. Although it's hard to catch, Eros turns on a similar computer on his ship right before the climax, so the humans and aliens understand each other during the final confrontation.
Inside the flying saucer, Eros turns on a televisor which shows Inspector Clay carrying Paula Trent. There is no TV camera following Clay. In Earth technology, it is impossible to get TV signals out of nowhere. But as the televisor is part of an advanced alien technology, it can do whatever the writers say it can do.
The actress playing Tanna barely restrains genuine laughter during Eros' "Stupid! Stupid!" tirade.
The circular slide rule hanging on the wall in the flying saucer is the same one hanging on the back wall of the cockpit of Trent's airliner.
During the attack on the UFOs, the army officer with the binoculars casts a shadow on the "sky" backdrop.
During the first briefing between Eros and "His Excellency", the latter stops talking mid-sentence twice, and obviously has to read his lines from a hidden manuscript on his desk before he can continue.
The tombstones in the cemetery are too close together for there to be room for bodies.
The ladders on the UFO go nowhere. You have to hang on & there's nowhere to grip (& they're set4 feet above the ground).
In one scene two different screams come from Paula's mouth at the same time.
The Old Man walks into the street and is heard to be hit by a car, but his shadow is still on the ground.
When police officers Kelton and Larry rescue Paula from Inspector Clay, she tells Kelton, "Oh, I'll be alright. Take care of the others." Her mouth is not moving.
In the cockpit when the plane moves from side to side, the movements of the set and of the spotlight are out of sync.
Inside the cockpit, the rim of the spotlight is visible for the duration of this and subsequent shots.
As the camera moves back in the scene outside the house where Jeff tells Paula to lock the doors, you can hear the cameraman's footsteps while the characters are standing still.
Someone's hand (either that of the stewardess or a crew member) from behind touches the shower curtain in the cockpit of the plane as the pilot says, "You better radio in for landing instructions, Danny".
The map on the wall of Gen. Roberts' office, which is supposed to be in the Pentagon, is clearly imprinted on the bottom left-hand corner with a large logo of the Santa Fe Railroad. Later, when he points out something to Col. Edwards on the map, the words "Santa Fe" have been taped over.
The scenes of the military attacking the flying saucers with artillery are obviously taken from stock footage of the Korean War. You can even see the thatched huts of a Korean village in the background, even though the action is supposedly taking place in California.
Stock footage of rocket launchers is used to show the attack on the flying saucers, which are up in the air. The rocket launchers are ground-to-ground weapons. Also, one of the rocket launcher vehicles shown is a Russian 'Katyusha' truck, filmed during the Russian counteroffensive during WWII.
The outdoor location, where the gravedigger scenes were shot, has no tombstones, crypts, or mausoleums anywhere.
Dan Clay is called "Inspector". Although San Francisco and a few other cities use the title "Inspector", virtually every police department in California--including Los Angeles, Burbank and San Fernando, where this was filmed--uses the title "Detective".
General Edwards tells Colonel Roberts he could be in hot water because he acknowledged that flying saucers were real, violating official government policy. However, this conversation takes place after the flying saucers flew over Los Angeles and Washington, D.C. in broad daylight, where they would have been seen by many thousands of people.
Boom mic shadow is clearly visible at the top of the screen the first time the pilots encounter the flying saucers.
Seen in shadow when the cockpit is lit up by the flying saucer.
Jeff describes the disc-shaped flying saucers as "cigar-shaped".
Eros says: "A ray of sunlight is made up of many atoms!" Light is made up of photons, not atoms.
General Roberts says that the alien radio messages are garbled because "atmospheric conditions in outer space often interfere with transmitting." Space is a vacuum, and thus has no "atmosphere."
From Eros' big speech (at 1 hour, 5 minutes, 53 seconds): "Then your scientists stumbled upon the atom bomb, split the atom. Then the hydrogen bomb, where you actually explode the air itself." Edward D. Wood Jr.'s science is pretty weak here. The hydrogen bomb is a fusion bomb which works with tritium; it has nothing to do with "exploding the air." An advanced alien scientist would not make such an absurd statement.
Criswell's opening narration (where he can be seen reading off of cue cards) begins: "Greetings, my friends. We are all interested in the future, for that is where you and I are going to spend the rest of our lives. And remember, my friends, future events such as these will affect you in the future." A moment later, though, he is placing the same events in the past, telling how "what happened on that fateful day" must no longer be kept secret. In the next paragraph he says it's sundown when it's obviously broad daylight.