Duchess Kate and Prince William's Christmas card contains a bizarre error

Prince William and Duchess Kate's family Christmas card proves just how perfect their family really is.

The photograph includes their two children, Prince George and Princess Charlotte, who are adorably dressed in their finest blue attire. Kate, with no baby bump in sight, donned a powder blue, two-piece Catherine Walker ensemble. William looked absolutely dapper in a navy blue suit.

However, some eagle-eyed fans pointed out an imperfection in the family's seasonal greeting. It seems as if Kate, 35, is missing her right arm in the snapshot.

"The more I look at this picture the more freaked out I get that you can’t see Kate’s other arm," one user wrote.

Another began a hashtag adding: "#WhoHasKatesArm? Has anyone seen Kate's right arm? Did she lose it somewhere?"

While another user added a zinger about Kate and William's lack of affection: "'Where is Kate's right arm? Can't be behind the Prince because they don't show PDA."

However, one Twitter user offered a possible solution to the bizarre mystery.

"I always rest my arm up the middle of my husband’s back ... I imagine that’s where Kate’s is."

Kensington Palace shared the sweet snapshot of the family earlier this week, and it's the last Christmas card before baby No. 3 arrives in April.

"The Duke and Duchess of Cambridge are pleased to share a new photograph of their family. The image features on Their Royal Highnesses' Christmas card this year," the caption reads alongside the photograph taken by Getty photographer Chris Jackson.

For more on the royals' Christmas plans, check out the video above!