This story takes place on Thoros Beta, which was mentioned by Sil in Vengeance on Varos: Part One (1985)/Vengeance on Varos: Part Two (1985).
Christopher Ryan (Kiv) and Trevor Laird (Guard Captain Frax) are among 29 performers that have appeared in both Classic Who and Doctor Who (2005). Laird had a semi regular role in the David Tennant Era as Martha Jones' father.
This four-part story within the Trial of a Time Lord season is commonly known as "Mindwarp".
In keeping with the "colour coding" of the Doctor's cravats, this story sees him wearing his red cravat, consistent with its events leading directly up to the start of the trial. This is its earliest chronological appearance within his time stream, although he wears it throughout the court room scenes, from the previous story through to the end of The Trial of a Time Lord.