Fans of 'The Crown' are wondering if this moment in the new season was a mistake

Royal watchers were treated to a new season of “The Crown” Sunday, as the hit drama returned to Netflix for a fourth season filled with a few new faces, including one cameo they never saw coming.

Fans have been abuzz about Emma Corrin as princess-to-be Lady Diana Spencer and Gillian Anderson as Margaret Thatcher since the first trailer for the season dropped over the summer. But now, after watching the first few episodes, everyone’s talking about a mouse spotted in the House of Windsor — and whether or not the royal rodent was meant to be there at all.

Shortly after the season made its debut, fans took to Twitter to exclaim about the creature seen scurrying across a rug in Buckingham Palace — right in front of the Queen Mother, played by Marion Bailey.

Does the set have a pest problem that slipped by everyone while filming and editing, much like the anachronistic coffee cup that stirred up so much drama during the final season of “Game of Thrones”?

Well, that’s one theory.

Many viewers posted messages meant to inform Netflix about the surprise appearance, as if the network had no idea. One fan wondered, "Was the quick cameo of a mouse in The Crown (episode three) intentional? I need answers."

Some fans insisted the rodent was actually a rat, and that it was there as a metaphorical reminder of the trouble that went down after Diana joined the royal family — after all, the episode in question focused on Prince Charles (Josh O’Connor) popping the question, as well as his off-and-on flame, Camilla Parker Bowles (Emerald Fennell), befriending Diana.

But the most entertaining theory put forth so far might just be the one that insists that, not only was the rodent intentional, it was actually a tour de force performance from yet another brilliant British actor.

Whatever the truth is, Netflix isn’t clearing things up. In response, the network simply tweeted, “Outstanding Guest Actor In A Drama Series?”