Every 'Doctor Who' Easter Egg You May Have Missed in 'Power of the Doctor'

Jodie Whittaker's run as the 13th iteration of the Doctor has come to an end with The Power of the Doctor, the centenary special.

The episode proved to be a veritable feast for fans of the iconic science fiction show, particularly those familiar with theclassic Dr Who era, which aired on the BBC from 1963 to 1989.

A number of Easter Eggs, references and cameos were made in Whittaker's swan song, and some viewers may have missed them.

Every 'Doctor Who' Easter Egg You May Have Missed in 'The Power of the Doctor'

The Power of the Doctor saw Whittaker's Doctor work to save the world from the double threat of regenerating Cybermen and the Daleks, which had both united against the time lord thanks to the Master (Sacha Dhawan).

Facing her biggest adversary, the Doctor needed all the help she could get as she was put through a forced regeneration while fighting a war that could have led to the end of humanity as we know it.

1. Ace and Tegan Return

Classic Who companions Ace (Sophie Aldred) and Tegan (Janet Fielding) returned to Doctor Who to help Whittaker's Doctor during her battle against the Cybermen and the Daleks.

The pair were drawn back into the Doctor's sphere by the Master, though neither of them knew that until the villain's plans were fully underway.

Ace was a companion to Sylvester McCoy's seventh Doctor, while Tegan was with the Doctor when Peter Davison portrayed the fifth version of the character.

Both Ace and Tegan were able to reunite with the version of the Doctor they remembered thanks to a hologram created by the time lord that changed from Whittaker's Doctor to the companions' respective Doctors.

Not only that, but both Ace and Tegan made multiple references to their characters' backstory, with Ace wearing her iconic bomber jacket and wielding a baseball bat to fight off the Daleks, while Tegan referenced her role as an air stewardess.

2. Doctors Old and New

When the Doctor is forced to regenerate she's taken to another plane, an apparent afterlife for the time lord where she encounters old versions of herself.

David Bradley once again portrays the First Doctor, after portraying William Hartnell's Doctor in The Doctor Falls and Twice Upon a Time.

Other actors to return included Davison, McCoy, Colin Baker and Paul McGann. Baker played the sixth incarnation of the Doctor, from 1984 to 1986, while McGann played him in the 1996 Doctor Who film.

At the end of the episode, Whittaker regenerated into the 14th version of the Doctor, which saw David Tennant return to the role he originally played as the 10th Doctor from 2005 to 2010.

3. More Than Just an Outfit

When The Master makes The Doctor go through a forced regeneration it results in the time lord's arch-nemesis taking her place, essentially becoming the fourteenth Doctor for a brief time.

Now as the Doctor, the Master decides to change clothes and goes into the Tardis to find a new outfit, and he comes out with an amalgamation of multiple items of clothing that The Doctor has worn over the years.

He wears the question mark jumper, shirt and tie that McCoy's seventh Doctor wore, the scarf that Tom Baker's fourth Doctor used, and even accessorizes with the celery stalk that Davison's fifth Doctor had.

The Master's Doctor also plays the recorder that the second iteration of the Time Lord, originally played by Patrick Troughton, would use to help him think.

4. Companions Anonymous

The end of the special episode also saw old companions of the Doctor from various years of the franchise, including Ace, Tegan, and Whittaker's companions Yaz (Mandip Gill), Dan (John Bishop) and Graham (Bradley Walsh).

But that wasn't the most surprising of cameos in the episode, as William Russell returned to reprise his role as Sir Ian Francis Chesterton, who was a companion for Hartnell's First Doctor from 1963 to 1965.

Doctor Who's Centenary Special is available to watch on BBC America.