This is why people only just started noticing all the mistakes in 'Friends'

Over the past couple of years, you may have seen stories popping up about mistakes in Friends that no one had ever noticed. 

Yup, even 12 years after the season finale of Friends, fans are still spotting small blunders and mistakes in the beloved 90s sitcom!

Like when Courteney Cox a.k.a. Monica, is blatantly replaced with a double:

Or in Season 9, when a stand-in for Rachael appeared behind Joey and it clearly wasn't Jennifer Aniston:

So, why are people only noticing these mistakes now after all these years? It may have something to do with the hours of binge-watching we can do in 2016 thanks to the internet, but there's an actual reason why we didn't see them until now.  

Turns out, these mistakes weren't actually visible in the 90s. Since Friends was made in the days before widescreen, it was not designed to view on widescreens (and these days literally everything is in widescreen ratio). Likely when the episode aired on TV in the 4:3 ratio, a stand-in would not have been seen in that format size.