Doctor Who: 20 Things You Didn't Know About The Tenth Doctor
12. His Regeneration Actually Destroyed The TARDIS
The Tenth Doctor's regeneration sequence is one of the hardest to rewatch, because it stirs up all the feels.
After bidding his companions farewell, Ten regenerates into Eleven in a burst of light and energy, which rips the TARDIS apart.
And we don't just mean in the world of the show, as the actual set also suffered during this scene.
The pyrotechnics set off during Tennant's regeneration sequence actually damaged the Time Rotor of the TARDIS set (that's the thing in the middle that goes up and down).
As a result, a new one had to be built, but as they were redesigning the TARDIS interior anyway, it really didn't matter.