To celebrate 20 years, this episode was made, under the premise that all five Doctors would feature.
As it turned out, with the first actor to play the Doctor (William Hartnell) being dead at the time, he was in need of a replacement. Secondly, Tom Baker, the fourth Doctor, refused to take part, so he was explained away using some footage from an unseen episode called Shada. I wish I could have said he was “cunningly written out” – but I can't. It was quite lame.
Overall a good storyline, and a nice smattering of former companions and well-established villians return for this one. One thing I have yet to work out is why this is the 25th Anniversary edition – because it was screened in 1983, 20 years after the original episode in 1963.
Two discs in this one, the first contains the episode as it was shown in 1983, plus some bonus features, the second contains a version that was upgraded with better effects in 1995, as well as more bonus features, and a rather pathetic easter egg.
For concept alone however, one of the best of it's time.