Doctor Who Christmas special: First look at Peter Capaldi's final outing
The release of the trailer coincided with the cast appearing at Comic-Con in San Diego on Sunday, where they talked about the upcoming episode, the last series and looked back at Capaldi's time on the sci-fi drama.
Gatiss described the Christmas special as being "a Christmas episode without being overtly Christmassy - it's very happy-sad".
He added: "[It's] a fantastic episode and we had a great time doing it. It was a lovely way out."
It will be the third time the Sherlock actor and writer has appeared on Doctor Who, after previously starring in episodes in series three and six.
Mackie also confirmed the festive episode will be her last appearance on the show.
Analysis - Lizo Mzimba, Entertainment correspondent
Twice Upon a Time is the final episode for Peter Capaldi's Twelfth Doctor and for outgoing showrunner Steven Moffat. Both have been huge Doctor Who fans for most of their lives, and their final story is clearly a love letter to a show that means a huge amount to both.
This first trailer begins with original footage of the First Doctor, William Hartnell, from 1966's The Tenth Planet (episode two if you're interested), which then mixes through to David Bradley who plays him in this story.
But it also shows a glimpse of a scene with the First Doctor and his assistant Polly from episode four - Hartnell's final episode before Patrick Troughton took over. Sadly that episode is one of the dozens that are still missing from the BBC archives.
The minute-long teaser also makes clear that this Christmas story won't just be accessible to long term fans. Bill will be back, after she was last seen heading off to travel the universe with student-turned-space and time traveller Heather.
The trailer also shows actor and writer Mark Gatiss making another Doctor Who appearance. In 2007 he played Professor Lazarus, and he also briefly popped up playing a different character in 2011.
Comic-Con fans were shown a
three-minute goodbye video for Capaldi, thanking him for his time on the show, which led to a standing ovation.
The actor praised writer and executive producer Steven Moffat, saying: "Every shot you saw there came through his gentleman's mind. The message of the show comes from his heart."