Continuity: In the first scene after the introduction, in full daylight, Russell remarks to Carol that they have been "married two hours." In the next scene, later the same day, she tells her father that they got married "last night."
Factual errors: The animated diagram shown to the audience while Russell is dictating his memo depicts satellites in circular orbit at different altitudes with the same period, which is impossible.
Plot holes: Russell makes a tape recording of what he fears will be his last message. He mentions that the flying saucer sound can be found on the same tape, and says he is stopping recording because the machine's battery is running low. For no reason he then switches the recorder to playback, without rewinding. Its offspeed playback then reveals the message in the sound. This means he must have been placing his message on a part of the tape where, if the battery had not run low, it would have obliterated the sound.
Continuity: During the offspeed playback, the reels are turning at close to normal speed, certainly at least half normal. For the high-pitched sound we heard earlier to have concealed an unnoticeable spoken message, the speed discrepancy would have had to be more than a factor of 10.
Factual errors: The language translation computer shown is a differential analyzer, a special-purpose analog device. It could not be programmed for such a task.
Factual errors: Mercury is at perihelion every 88 days, not "twice every 3 months."
Factual errors: While overall levels of solar activity do have an effect on climate over the long term, and a major disturbance in solar activity would affect weather, it is certainly not correct, as stated, that simple sunspot activity has "a direct effect upon our weather."
Audio/visual unsynchronized: During the final clamactic battle in the skies over Washington, there are several shots of Dr. Marvin speaking into a hand-held microphone. You'll notice as his lips move that what he is saying clearly doesn't match the dialogue heard.
Continuity: In the opening scene as Russell gets in and out of the car, the car seats change colors.
Continuity: The flying saucer chases a B-29 Superfortress that turns into a B-17 Flying Fortress when it is destroyed.
Continuity: While they are aboard the flying saucer, Carol Marvin is shown to be hugging her husband in some shots and not in others.
Audio/visual unsynchronized: In the opening scene, a military jet is seen flying, but the sound effect is of a propeller-driven plane.
Continuity: The position of the tape when playing the flying saucer sound changes inconsistently from one shot to another.
Continuity: When they are leaving the lab for D.C. with the new gun the truck stops by trees in a level field but when the alien destroys it the truck is by a steep hill.
Continuity: When Maj. Huglin shoots the alien that has just killed Prof. Kanter the alien falls forward and it's helmet comes loose but when they turn alien over to examine it the helmet is back on tightly.
Factual errors: In his taped report, Dr. Marvin states that the satellites will be placed in orbit by multi-stage rockets, however, the rockets in the launch scenes are single-stage Viking and V2 rockets.
Continuity: In the first scene Dr. Marvin is recording his report on the tape recorder when the saucer appears, as the sound of the saucer becomes audible, he says "Do you hear something? Listen." A moment later after the saucer has "buzzed" the car, he tells his wife "Pull over." However, when they play back the recording, all that is heard is the saucer sound; the two comments are not on the tape.