Continuity mistake: In episode three, the readout strip dangling from K-9's mouth shortens between when he shoots the infected crewman and shoot Leela.
Continuity mistake: Lowe's "frozen" makeup changes between when he emerges from the freezer and when Leela brings him a cup of coffee.
Continuity mistake: The countdown clock in Marius' lab speeds up and slows down as needed for the plot.
Other mistake: The Brigadier says UNIT HQ is 'a Top Secret establishment'. It is, in fact, so secret that it has a large sign outside informing the world not only of its function, but also the name of the commanding officer.
The Doctor: You can't rule the world in hiding. You've got to come out on the balcony sometimes and wave a tentacle, if you pardon the expression.
Planet of the Spiders - S11-E5
Trivia: The first thing the Third Doctor does on-screen is collapse out of the TARDIS, which is also the last thing he does in that incarnation.
Question: In which season and episode is Gallifrey destroyed, or is it just a shocking new plot development for the new series?
Answer: It was never destroyed on-screen; it was intact at the end of the TV movie, and destroyed by the start of the 2005 series. It was destroyed in the novel "The Ancestor Cell," but in a completely different manner to what happened in the series.
DaveJB