They'd had Gary Russell as continuity checker before, GARY FUCKING RUSSELL (dunno if it still is) and made huge gaping errors with him
I wasnt going to do this, but you still need convincing
! Clue : You've seen the FutureDoc before. In Eleventh Hour The Doctors Sonic is "found" in the Hidden Room, all beaten up by Prisoner Zero.
This is casually brushed aside by saying he "must have dropped it" We saw every second of what happened. At no point did he drop it.
! There is more going on behind the scenes, concerning FutureDoc and FutureDoc has been in more episodes, and will be in more to come
And another clue, I'll give you is very clearly presented in Episode One, the problem is people misunderstand it, which is understandable,
as at the time it doesn't seem much. But, another clue (concerning 11th Hour specifically) "Shadows".
There are also different clues in TBB, specifically after the 9 minute mark.
Look out for him In VOV, and also there's an ominous ending scene concerning a series arc