Warning! The following contains spoilers for the Doctor Who Christmas special! Read at your own risk!
Peter Capaldi gave his final series regular performance as the Doctor on last night's Doctor Who Christmas special, and it was one for the ages. On top of his awesome farewell speech and regeneration, Capaldi's Doctor also got to meet back up with old friend and former companion Clara Oswald. The details as to how are a bit complicated, but ultimately, it meant fans got to see Jenna Coleman in the show once again. While as amazing as it was surprising, it was a cameo that now-former showrunner Steven Moffat was not easy to pull off:
I had to phone Jenna, who was incredibly busy on Victoria. Incredibly busy. A ridiculous schedule. I mean she was well up for it, but it was complicated to arrange.
Jenna Coleman's commitment to Victoria was one of the main reasons many Doctor Who fans initially believed the actress wouldn't be able to commit to a return, although rumors still swirled nonetheless that she was going to appear. Turns out those rumors were true, although it was really understated just how many hoops Steven Moffat had to jump through to make it happen. Moffat tells Radio Times Coleman's bit had to be filmed after production had wrapped on the episode "Twice Upon A Time," and then had to be inserted into the Christmas special afterward via special effects. The scene ended up being the final thing Moffat would shoot for the series, so fans can now think of that little extra effort as his send-off gift to fans for years to come.
Steven Moffat's effort of bringing back Clara wasn't just a gift to fans of Doctor Who though, it was also a gift to Doctor Who lore itself. The Testimony drawing upon memories to show her image to the Doctor jump-started his mind and brought back all the memories he had of Clara Oswald that had been previously erased. While the moment didn't suddenly free up Jenna Coleman's acting schedule and make her more available to appear on the series, the fact that the Doctor can now remember her again will certainly make it easier to bring her back in the future should new showrunner Chris Chibnall be able to work anything out for her down the line.
Doctor Who is set to return to BBC America for Season 11 sometime in the fall of 2018. Anyone wishing to see which shows are set to premiere or return in the new year can visit our midseason premiere guide and find out. Those curious as to what shows still haven't premiered yet but are due to before the end of 2017 can see what's left by visiting our fall premiere guide. For a look at which shows got dropped in the past year and a brief explanation as to why visit our cancellation guide.