When the giant bird attacks the squadron of planes sent to destroy it, the planes that it has in its mouth are delta wing whereas the fighters were of the standard wing design.
At 54:52 while the search for the nest begins, the 3 are riding in an everyday helicopter. At 55:01 the helicopter has changed to a military heavy lift type of helicopter.
After Mitch causes the explosion in the lab by using the mu mason projector, Sally and Dr. Noymann stand up in the next room and rush into the lab where Mitch lays prone on the floor. Sally passes through the door into the lab first. In the next shot from within the lab, Dr. Noymann is passing through the door first.
At 0: 56 when 'Mitch' & 'Sally' are shooting the egg, Sally's first shot is directly next to Mitch's shot. A few seconds later the shots are shown spaced widely apart. Seconds later when Mitch takes his second shot, the hole Sally shot in the egg is gone.
The B-25 in flight changes its markings between shots, and the mu-meson cannon is clearly not installed.
Any five random points on a map can be turned into a spiral without any underlying pattern existing.
The scene which shows Big Ben in London, with traffic moving over Westminster Bridge including trams among the traffic.
The last vintage trams to run in London were in 1952 and means that movie scene was pre-1952, but this movie was made in 1957, which means the woman screaming in terror predicted the big bird's attack at least 5 years before it happened.
If the gigantic bird were really from an antimatter galaxy, it could not enter the Earth's atmosphere. Its atoms would be comprised of positrons, anti-protons and anti-neutrons. These would immediately undergo annihilation events as they came in contact with any of the regular atomic matter of the air (molecular nitrogen, molecular oxygen, water vapor, etc.).
However, the film states that the bird itself is not antimatter, but uses an "energy screen" of antimatter, and that it switches off the shield to use its claws and beak. The scientist says if the bird had been antimatter it would have exploded, but doesn't explain why the antimatter shield is not affected.
At 1:06, the bird grabs a train and pulls it up into the air. It's obviously a toy train. A chain of several cars dangles from the bird's beak. Train cars' couplings could not hold a car vertically.
Just before the CAB plane is attacked (0:27), the narrator gives the time as "oh-eighteen-fifteen" which is meaningless in military time. A moment later, he gives the time in the correct terminology, "oh-eight-sixteen (0816)."
As Mitch's plane goes into a power dive, it briefly moves backwards as the model wires get stuck.
Due to use of footage from Earth vs. the Flying Saucers (1956), a flying saucer can very briefly be glimpsed in Grand Central Terminal during the bird's attack on New York City.
Light hand-drawn X's can be seen on the map before Mitch draws his own X's, indicating where he is supposed to make his marks.
When the jets are attacking the bird, several shots of the planes are reversed to make it seem as though they are flying in the opposite direction, as the writing on the sides of the planes in these shots are backward.
In several close-up shots of the bird's head, the wires controlling the puppet are clearly visible.
At 43 minutes Mitch is using a slide rule to do a computation. But he never moves the central slide, it is in neutral position throughout. Nothing could be computed that way.
Sally is using a slide rule to draw, near the end of the film. 58:52
When Lt. Gen. Edward Considine orders a general air alert against "the claw", the film clips of the F-86 firing rockets at it, notice that one of the clips is reversed! The nose ID, "Air Force FU 85T" just a few moments later is reversed, reading "T68 ECROF RIA".
As the plane carrying the meson cannon flies towards the bird (who is on top of the United Nations building in New York City), the footage of the plane shows it over San Francisco.
The Capitol Building can be seen fairly close outside the window of Considine's office at the Pentagon. The two buildings are actually more than a mile apart on opposite banks of the Potomac River.
Many of the scenes are supposedly in the Adirondacks of upstate New York. But the vegetation and terrain are clearly California.
When the characters are in the helicopter searching for the monster's nest, Mitch calls Pierre "Pepe" once though he gets the name right all the other times.
No world-destroying space-bird would be so foolish as to try and deal with two people who had just shot its only egg by merely dropping a few leafy twigs on them.
When Mitch and Sally are leaving Pierre hurriedly, Mitch oddly makes reference to the 'social amenities'. He clearly means 'social niceties' - quite different.