Other: What happens to Tegan's bag when the plague victim transforms into the cavalier? It doesn't appear to be left behind, even when the cavalier later vanishes.

Visible crew/equipment: As the Doctor is watching Will emerge from the priest-hole, look over his shoulder at the far corner. Someone or something appears to be moving in the shadows there.

Revealing: When the crack in the wall breaks open, the wall wobbles rather obviously.

Audio problem: Davros' lips don't move when he says, "Now for the Daleks," just before he releases the Dalek-killing virus.

Revealing: When Lytton and his men approach the self-destruct chamber in episode three, the door is closed in front of them. It wobbles as it closes.

Other: When the Doctor's mind is scanned, we see his previous incarnations and companions, but Leela it not shown. Katarina is represented by a black and white photograph.

Revealing: When the Doctor is shooting the Dalek creature hidden under the coat, he is obviously using blanks because when you see the coat there are no bullet holes in it.

Continuity: When the Doctor and Peri first land on Androzani, mountains are seen in the background. They disappear when Peri picks up the silica. A couple of shots later, they're back. (This mistake was mentioned on the DVD commentary; the mountain effect was left out for financial reasons).

Revealing: It's already been mentioned that Peri bounces off a mattress, but watch what happens when the Doctor walks over to see if she's all right. The 'cave' floor visibly moves under his foot.

Visible crew/equipment: The boom mike is visible at the top of the screen when one of Jek's androids is handing spectrox to the mercenaries. The shadow of the boom pole is also visible on the roof beam.

Continuity: When the Doctor is climbing through the tunnel to the Queen bat, note the question mark on his lapel: the image is reversed.

Revealing: When Peri falls into the spectrox nest, watch for her to reappear as she bounces off a mattress.

Revealing: When the Doctor is looking for a way to break through his manacles, he brushes against the machine with the bright light that he eventually uses to cut them. When he does, it wobbles when it obviously should remain motionless.

Revealing: In the very first shot of Morgus' hand-held computer, it's obvious it's a TV remote. Look for the controls for contrast and tint.

Factual error: Sharaz Jek's monitor that displays the tunnels and his androids is inaccurate. The white blobs are, as we learn later, supposed to represent his androids. He tells the Doctor that the green area is held by the army, yet on the screen the green area is populated by androids, so they could not have had control.

Revealing: When Stotz cuts a hole in his ship's door, you can see that the inside of it is made of white polystyrene. They painted the outside of it but obviously forgot about the inside. Also listen to the sound it makes when Stotz punches the hole through - it sounds exactly like polystyrene.

Factual error: When the Doctor is trying to land the ship, from the video screen it appears that they are moving towards the planet way too fast to make such a safe and quick landing. Also, the ship doesn't seem to have even penetrated the planet's atmosphere yet it lands seconds later.

Plot hole: Azmael doesn't recognise the regenerated Doctor (In the shape of Colin Baker) whereas on most other occasions other Time Lords do recognize each other through telepathy. This is odd behaviour by Azmael, considering that Azmael and the Doctor HAVE actually met before, and possibly more than once. (Azmael last met the Doctor in the Doctor's fourth incarnation, and was the best teacher the Doctor ever had. On that occasion, Azmael got drunk.).

Revealing: The bottle of acid that the Doctor throws at Mestor breaks open well before it hits the shield that Mestor is projecting around himself.

Audio problem: In episode 1, The Doctor hits something on the central console (not the door control) and walks towards the door. The door doesn't open, but the sound of the door opening is still heard.