"So you escaped from Castrovalva..." That's the only explanation we get for the recently undisguised Master's miraculous ability to get out of what looked to be a very sticky situation at the end of the Fifth Doctor's debut adventure. While it would be bogging down the plot to have to explain past adventures, it's the start of a troubling trend in Doctor Who in which each seemingly impossible escape by The Master is glossed over with less and less explanation.
There's some truly terrible scenes set within the sanctum in which to Xeraphin bitch at each other in an unnatural fashion while The Doctor is left to explain what's going on to the viewer. One supposes he's giving a play-by-play to Tegan and Nyssa, although the latter already knows full well what's happening, seeing as she's been a poor man's Deanna Troi throughout most of this story, acting as cipher for the Xeraphin. It all looks like bad, Season One Star Trek: The Next Generation on a Blake's 7 budget, and is one of the few times (yes, it hasn't happened often) that's I've really been embarrassed for Doctor Who.
And yet, Time-Flight is almost single-handedly rescued by Captain Stapley. His pluckish good nature, loyalty to The Doctor, and ability to rise to the occasion makes him one of the great pseudo-companions ever in Doctor Who. He has perhaps the most laid back reaction to the otherworldly dimensions of the TARDIS ever (is anyone even impressed anymore by the fact that this thing is bigger on the inside than it is on the outside?), and he even has a go at flying the thing. Why isn't he listed as a companion, and yet Sara Kingdom is? The scenes with Stapley, Bilton, and Scobie are probably my favourite parts of what has been a very weak effort to send Season 19.