Corrected entry: When the "human suits" are used, there is no zipper seen. When they go to open up, there's suddenly a zipper in evidence.
Corrected entry: After the Slitheen realize that the Doctor's ruse with the alcohol is a ruse, the metal shielding around the windows and doors slams shut quite quickly. Later, while talking with the Slitheen again, the shielding closes much slower. Seems like their motors run at speeds determined by the dramatic tone of particular scenes.
Correction: When we see the doors closing slower, the scene is happening in slow motion which is an artistic decision not a mistake.
Corrected entry: The reference to the UK needing special "secret launch codes" from the UN is a compete fiction. The UK could launch a nuclear strike without needing permission from the UN. The UK would, however, need permission from the United STATES [not United NATIONS] to launch a nuclear strike, as the Polaris missiles are leased from the US Government [although the UK owns the warheads].
Correction: This "mistake" is actually part of the fictional plot. The dialogue states that the reason the UN has the nuclear launch codes is because of previous poor history by the UK when handling them, referencing "Robot" from the old series of Doctor Who.
Correction: This is alien technology. There is also no way these suits should fit around these aliens but they do.