10 Times Doctor Who Broke Its Own Canon

When UNIT was first introduced in 1968's The Invasion, there was a broad suggestion that they were a military organisation from a few years in our future. This largely holds throughout the Pertwee era, and it also explains why Sarah Jane Smith states that she's from 1980 in Pyramids of Mars, which was broadcast in 1975.

Meanwhile, a retired Brigadier Lethbridge-Stewart is called back into service over a decade later in the serial Battlefield, which is set in 1997. All of this would be fairly watertight continuity-wise... if it weren't for the existence of Mawdryn Undead.

This notorious Fifth Doctor serial tells us that the Brigadier left UNIT in 1976. This is particularly problematic not just because it's four years before Sarah Jane's time, during which the Brigadier was still working at UNIT – but also because it totally breaks the entire UNIT timeline!

One of many ways this breakage occurs is if we look at the original Radio Times listing for The Invasion, which states that the story takes place in 1975.

So if the first appearance of UNIT was in 1975 and the Brigadier retired in 1976, that would mean the entire Pertwee era, Robot, and Terror of the Zygons took place in less than 12 months.

No wonder the Brigadier had a nervous breakdown!