Monica was replaced in an episode of Friends and people didn't notice until now

Just as sure as we’ve all breathed and slept, we’ve all watched every Friends episode dozens of times. But even though you probably know most of the episodes off by heart and could recite the scripts backwards, there might have been one thing you missed.

In the episode ‘The one with Rachel’s date,’ a double standing in for Monica can be seen during a conversation with Phoebe in Central Perk.

You can only see the Monica stand-in for a fleeting second, but it’s long enough to ruin the Friends magic.

And it’s not the first time:

I don’t want to do this.

I really don’t.

But fans have also spotted an imposter Rachel, too.

In the episode, 'The One With The Mugging,’ Rachel is replaced by a fraud at the side of the screen:

Gif via Decider

It turns out the sixsome we thought we knew and loved wasn't quite what we thought.

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