1. The Enterprise goes boom.

 

"Charlie X"

While the shadow of the boom mic can be often spotted on walls or in reflections, it does actually creep onto the screen in a few rare occasions. When Charlie catches up with Rand in the corridor to give her a present, the tip of the gray boom pops into the frame ever so subtly.

2. Some bridge work

 

"Where No Man Has Gone Before"

Early in the episode, when helmsman Gary Mitchell calls guest star Sally Kellerman a "walking freezer unit," piping and rigging from the set can be seen in front of the bridge console.

3. The edge of Galileo

 

"The Galileo Seven"

The edge of the facade is briefly revealed as the frame shakes aboard the shuttle. You can briefly see a bar of black behind Leonard Nimoy and a flicker of the surrounding set.

4. A wooden starship

 

"Errand of Mercy"

In the opening, as the Enterprise is attacked by a Klingon vessel, you can see that the floor behind Nimoy has not been painted. The bare wood is exposed on the elevated part of the bridge.

5. Shouldn't you be meditating, Spock?

 

"Amok Time" 

In the middle of this classic season two opener, Spock enters a meditative state called plak tow. We see close up shots of him deep in the trance, with his hands clutched before his face as his eyes practically roll back into his skull. However, after T'Pring chooses Kirk as her champion, there is a cut to a wide shot. In the background, you can see Leonard Nimoy waiting around with his hands behind his back.

6. Batten down the bridge!

 

"The Changeling"

In the prologue, when a green bolt of light slams into the Enterprise — Red alert! Here we get a taste of that classic disaster technique of shaking the camera as the cast flails around on set. However, it must have been a pretty hard blast, as the helm console lifts off the floor.

7. They have a L.A. on Neural, too?

 

"A Private Little War"

The gang is on the primative planet of Neural. In the final act, Nona is being attacked by some tribal toughs, who look a bit like Daniel Boone in pastel pajamas. She tries to use Kirk's Phaser against her attackers. As they struggle, Los Angeles can be seen off in the distance in the smog.

8. A tight squeeze

 

"Spock's Brain"

At the start of the third season, the cast received some new Starfleet uniforms. Out went the velour. The new tunics were a much tighter double knit material. In the season opener, the much derided (and underrated) "Spock's Brain," when the crew beams down, you can clearly see William Shatner's tummy-squishing girdle under his top.

9. A substitute Chekov

 

"Let That Be Your Last Battlefield"

After the red alert, as the Enterprise is on a collision course with an invisible ship, there is an insert shot of some stock footage. Chekov has suddenly disappeared, replaced by a redhead with a long neck. Who is this guy? No worries — Walter Koenig is back in the next shot. 

10. Kirk flips out.

 

"The Way to Eden"

You remember the episode with the space hippies, right? Midway through, as Kirk exits the sick bay, there is a close-up shot of Shatner. The image has been clearly flipped, as his uniform insignia has jumped to the wrong side of his uniform, in reverse. Later, outside the shuttle on the planet surface, it happens again.

SEE MORE: 9 MINOR GOOFS YOU NEVER NOTICED IN 'GILLIGAN'S ISLAND'

 

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