Visible crew/equipment: In the scene where Ian's pen vanishes, as he checks to see if he is being followed you can see a boom mic shadow on his coat.
Visible crew/equipment: When Susan runs out into the console room in a panic, the shadows of two crew can be seen on the wall.
Visible crew/equipment: In episode four, when Ian and the Doctor descend the stairs into Frankenstein's lab, you can see a boom operator and mic behind Ian, at the left side of the screen.
Visible crew/equipment: In episode one, when Dai Evans is on the telephone in the mine, an arm of a crew member appears to the bottom right of the screen, giving the actor his cue to speak.
The Monster of Peladon - S11-E4
Visible crew/equipment: When Azaxyr is setting his ambush for the miners in episode six, a studio light can be seen through a gap in the wall.
Visible crew/equipment: Early in the first episode, a huge power cable can be seen on the TARDIS floor. Maureen O'Brien even steps over it. This cable isn't visible in any other scenes.
Visible crew/equipment: Part 5, Kidnap: In the Sensorite lab, the Scientist shows the Doctor and Ian a collection of things left behind by the humans, who were killed in the spaceship explosion. When Ian flips through the family snapshots, the shadow of the boom mic passes over Ian's forehead. It happens again just as Susan blurts, "The City Administrator, of course!"
Visible crew/equipment: Part 4, A Race Against Death: While Susan is with Ian and the First Elder, Ian tells her, "The Doctor must have run into a snag..." When Susan replies that she's going to find out why, just as she stands up a boom mic becomes visible at the top right side of the screen, and it's pulled up out of view. Then, as the First Elder says, "I will have you conducted to the laboratory," the shadow of the boom mic is on his head.
Visible crew/equipment: Part 4, A Race Against Death: After the Doctor states he's going off on an expedition, John still struggles to warn the Doctor, and when the Doctor tells Carol, "Now you stay with him, I think he's getting better," a boom mic becomes visible at the top left side of the screen.
Visible crew/equipment: Part 3, Hidden Danger: When the First Elder tells the Doctor, Ian, and Susan about their refined aqueduct water beneath the city, Ian drinks some of it. Then just after the Doctor says, "Vintage water," the tip of the boom mic sweeps across the top of the screen.
100,000 BC - S1-E1
Visible crew/equipment: The studio ceiling and lights are visible at several times during the console room scene.
Visible crew/equipment: While The Doctor and Zoe are on the SIDRAT, The Doctor expresses hope to get the hang of its controls. When the SIDRAT materializes, in the shot facing the door as The Doctor pokes his head out to exit, the camera turns toward the right and there's a reflection of the moving camera and the camera operator walking behind the camera, at the right side of the screen. (00:08:25)
Visible crew/equipment: (Episode 5) After The Daleks plan to organize a full-scale search of the jungle at daybreak, when it cuts to The Doctor and Ian, the shadow of the boom mic moves around at the left side of the screen. (00:16:35)
Visible crew/equipment: (Episode 6) At the very end, after Vicki and The Doctor have watched Barbara and Ian's return to 1965 on the Time-Space Visualiser, when Vicki hugs The Doctor the moving boom mic casts a shadow at the top, left of the screen. (00:24:30)
Visible crew/equipment: When the Doctor and Ian enter the house in episode one, there is a shadow of the camera on the wall next to Ian.
Visible crew/equipment: In the fourth part, as the mortally wounded fighter is falling against the back wheel of the cart, the camera is positioned low and its shot is panned upwards, revealing the top of the cyclorama, a large concave backcloth that has been pulled around the studio walls (presumably BBC Studio 1) to give the impression of daylight in these studio-shot but supposedly external scenes.
Visible crew/equipment: When the group are thrown into a dungeon in Omega's palace, you can see tape in the corners which is holding the set together.
The Daleks' Master Plan - S3-E4
Visible crew/equipment: In Episode 2 when Marc Cory and the other Ambassador are talking, a figure who appears to be wearing Space Security Uniform (and this isn't Nicholas Courtney) and a stage hand walk by, and you can also see the end of the set.
Visible crew/equipment: At the beginning of episode two, the Doctor finds Ian unconscious with a very obvious shadow of the camera and cameraman looming over him.
Visible crew/equipment: At the end of episode 3, a venom grub starts chasing Ian. As it enters the screen however, you can see the actor under it crouching down.
Chosen answer: The Master is insane. If he can't control the universe, he'd rather see it destroyed.
Captain Defenestrator