In this episode, Zooey Deschanel guest-stars as Temperance Brennan's cousin. Throughout the episode, the cast often makes jokes about the resemblance of Zooey and Emily Deschanel's characters, even saying they could be sisters, when in reality they are.
When Booth enters the room to find Brennan talking to her second cousin, he assumes they are sisters. In real-life, Emily Deschanel (Brennan) and Zooey Deschanel (Brennan's cousin, Margaret) are in fact sisters.
While Bones is recovering evidence from an almost naked Booth, she wants to cut some evidence out of his hair. Booth yells out "Not the hair!" During David Boreanaz's run on Buffy the Vampire Slayer and Angel there were multiple jokes about his hair. Spike referred to him as "Haircut".
Daisy states that Rudolf must be a girl because male reindeer drop their antlers in winter (before Christmas). This isn't necessarily true. Gelded male reindeer drop their antlers later, additionally it is pregnant females who don't drop their antlers til later, non pregnant females still drop their antlers. Leading to the conclusion that Santa's reindeer are either gelded males or pregnant females.
Booth was shot in the chest in episode S03E14, yet there is no scar when Brennan takes his shirt off.