People left in shock after finding out real-life age gap between Keira Knightley and Chiwetel Ejiofor in Love Actually

Christmas films always get us talking, for better or for worse.

Perhaps you might have a relative who thinks the Grinch wasn't such a bad guy.

Or maybe you're on the look out for a cameo from Macaulay Culkin's brother in Home Alone.

We all love watching a Christmas film (Getty Stock)

But should you happen to switch on Love Actually, there's only aspect of the film that will leave you stunned.

And no, I'm not talking about the gut wrenching betrayal that Emma Thompson's character goes through.

In fact, it's the ages of some of the cast that have left viewers with their jaws on the floor.

Just in case you've not seen it, the Richard Curtis follows the complicated love lives of several couples through the holiday season.

One such couple is Juliet and Peter, played by Keira Knightley and Chiwetel Ejofor respectively.

Knightley was very young at the time of the filming, as she was only 18-years-old.

It was already strange enough for fans to learn that there were only five years between her and Thomas Brodie-Sangster.

That cute little kid that runs in the airport at the end of the film? He was actually 13.

Keira Knightley's age has left many viewers stunned (Universal Pictures)

Isn't that mental?

Almost as the weird is the age gap between Juliet and Peter, whose actor was 26 at the time of production.

That's a big age gap for a romantic pairing.

LADbible previously spoke to director Richard Curtis about the age gap, which he said 'didn't seem too peculiar' back in 2003.

He said: "I'm really interested in whether or not I would think ‘don't do that’ now. And that actually now we probably wouldn't have gotten someone as young as Kiera was in.

"The great thing now is that everybody is bold enough to say anything they don't particularly like in what you do - kind of gives you a filter these days.

"But on the other hand, I'm thrilled we cast Keira because I thought she was perfect. And I don't think she reads in the film as being a teenager, I think she reads as being about 23. But it's interesting that they were far apart."

Curtis' reading of the film is right - there's no indication in the film's plot that Juliet is meant to be a teenager.

Keira Knightley's age gap with her on-screen husband has left people shocked (Universal Pictures)

By the time the film had hit cinemas, Knightley had already starred in two box office hits - Bend It Like Beckham in 2002 and Pirates of the Caribbean: Curse of the Black Pearl in the summer of 2003.

This was coming off her small role in Star Wars: The Phantom Menace.

Talk about hitting the ground running.