[2] The episode premiered in the United States on December 7, 1997 on the Fox network, earning a Nielsen household rating of 12.8 and being watched by 20.91 million people in its initial broadcast.

The show centers on FBI Special Agents Fox Mulder (David Duchovny) and Dana Scully (Gillian Anderson) who work on cases linked to the paranormal, called X-Files.

In this episode, Scully, on Christmas vacation with her family, receives a mysterious phone call that leads her to a case involving a little girl that she believes to be the daughter of her dead sister, Melissa.

Around Christmas time, Dana Scully (Gillian Anderson) and her mother visit her brother Bill and his wife, Tara, who is expecting.

Scully traces the call to a nearby home in San Diego, where local police are investigating the suicide of a woman, Roberta Sim.

Roberta's husband, Marshall, is meeting with two dark-suited men inside his house, and has no desire to listen to and help Scully figure out what is going on.

The police search the Sim's house and find a used hypodermic needle, which Marshall claims was for daily injections for Emily's anemia.

However, the three were unable to develop any more ideas, and so they decided to instead feature Scully being visited by "earlier versions of her family members herself", resulting in the flashback sequences that pepper the episode.

Because the actress could not be calmed down, the show's producers were forced to recast the role and reshoot all footage featuring Emily in "Christmas Carol".

[4] Props specialist Ken Hawryliw claimed the biggest challenge in producing the episode was finding Christmas paper from the 1980s for the flashback sequences.

"[3] Anderson also admitted that another issue she had was that Scully "had no history with" Emily so she was unable to "play the kind of attachment I would feel if my own daughter, Piper, were going through the same thing.

[7] Robert Shearman and Lars Pearson, in their book Wanting to Believe: A Critical Guide to The X-Files, Millennium & The Lone Gunmen, rated the episode four-and-a-half stars out of five.

[8] Matt Hurwtiz and Chris Knowles, in their book The Complete X-Files called the episode "a showcase for Gillian Anderson's startling acting chops.