Revealing: In the basement lab scene at the end, George Grizzard's double's face is visible in profile several times.

Factual error: On the bulkhead of the ship's sickbay is a standard 12-hour civilian clock. It shouldn't be there. All clocks aboard U.S. Navy vessels show 24-hour military time.

Revealing: We see Redfield's car strike the invisible barrier from a side angle. It jerks to a stop and the hood flies up, but there's no other front end damage - until the angle shifts to a forward view, a shot of an identical car that had been previously wrecked. Now there's suddenly considerable damage to the front end, and the hood is in a different, much more crumpled position.

Revealing: When Mason puts the ID card back into the pocket of his dead duplicate, the "corpse" twitches its eyelids.

Visible crew/equipment: In the final shot of the ship ascending into space, one of the filament lines supporting the model is showing just above the saucer.

Visible crew/equipment: Just after the ship re-attains orbit, the shadow of a production crew member moving his arm can be seen on the wall at the upper right of the shot.

Continuity: When Jackie leaves the office, the clock reads 10:12. The ensuing continuous scene with Winter and Mr. Smith is almost 6 1/2 minutes long, yet at its end, the same clock has advanced only 2 minutes, now reading 10:14.

Factual error: In the opening scene, Horace painstakingly loads his six-shooter cap pistol with a six-cap round - then shoots his boss with it seven times.

Factual error: The colonists' planet has twin suns and, we're told, no night. We see the suns, side-by-side in the sky. But twin suns would not create perpetual day. Night/day is caused by the rotation of the planet on its axis, regardless the number of suns. In a binary star system, the two stars orbit each other around a central point in space. The planets would orbit around that central point too. In order for there to be no night, the planet would have to pass between the two stars, a process it would not survive. The gravitational forces of two opposing suns would tear the planet apart.

Continuity: During their conversation over tea, Mr. McKenzie tells the Ransomes about the other people aboard ship. One elderly couple, the Whiteaways, are sitting in the background in almost complete shadow - until McKenzie introduces them. Then we see them in sudden brilliant light, and they've shifted their seating positions relative to the table. When we cut back to the master shot, they're back in shadow and back in their original positions.