The scarecrow story is in some of the old comics. They wanted to do comics after The War Games, but Pertwee hadn't been cast yet, so they just kept on going as with the second Doctor, claiming he'd been exiled to Earth, but got away before they changed his appearance, until the Time Lords sent their scarecrows after him.
The second Doctor actually says that line in The Five Doctors before he meets the other Doctors; I think he says it because he's meeting the Brigadier out of order.
The second Doctor actually says that line in The Five Doctors before he meets the other Doctors; I think he says it because he's meeting the Brigadier out of order.