Viewers were excited to watch the series after it was released on Sunday (15 November), and couldn't help but notice a special appearance from the creature.
The mouse can be spotted in the opening of the third episode, titled "Fairytale", which shows members of the royal family waiting to hear from Charles (Josh O'Connor) about his proposal to Lady Diana Spencer (Emma Corrin).
As the Queen Mother (Marion Bailey) sits and waits by the phone, the mouse runs across the screen.
The show's fans have now been left wondering if this was intentional, with a viewer stating: "Was the quick cameo of a mouse in The Crown s04e03 (running 01:06) intentional? I need answers."
"Is that on purpose? There are rats even in the tidiest and most luxurious place," one viewer asked.
One person thought it was a good "symbol" for what they called "the royal farce", with another adding: "Can we talk about the literal rat that runs across the floor in #TheCrown season 4 episode 3?! Like is this symbolism?! An oversight!?"
"Someone else quipped: "The only character in the crown I truly identify with is the rat that scurries across the floor 1 minute and seventeen seconds into episode three of season four."
Following the premiere of the new season, many people were left feeling "conflicted" over Gillian Anderson's depiction of Margaret Thatcher.
Find a rundown of the show’s accuracy here.
