When scanning the history of TV shows, there are few that can rival the success and the impact of . It was a giant in its time, and it conquered the small screen in ways that few others could. The show's stars made millions, and thanks to a brilliant contract.No show is perfect, and this definitely applies to . , and some even make their way into the final cut of an episode. Some errors, however, can fly right over people's heads.Let's take a look back at a mistake from that most people seem to have missed.

'Friends' Is A Classic

In 1994, NBC was already having their cake and eating it too with the runaway success of , but things reached another level when they debuted . Fans were ready for another great NBC show, and wasted no time in becoming the most talked-about show around.

The cast was led by performers who weren't household names at the time, but you had better believe that they all became famous faces when the show exploded into the mainstream. Simply put, they were all dynamic in their roles, and their work each week elevated what was an already solid script.

The series has not aired new episodes in years, and yet, it remains one of the biggest shows on TV today. Streaming has given it new life, and because of this, new generations will continue to hang out at the Central Perk.

As timeless as the show is, it is certainly not free of error, and over time, fans have been able to spot some mistakes that made their way onto the final edit of the series.

'Friends' Had Some Mistakes

In this day and age, fans are always on the hunt for mistakes in movies and TV shows. Normally, once a mistake is pointed out, it makes its rounds online for people to look and laugh at. Because is constantly in rotation, people have been noticing more and more mistakes through the years.

One major mistake was noticed during the show's pilot episode. During the episode, a production blunder led to multiple Phoebe's being around.

Per , "The scene in question comes from the show’s very first episode, and sees Phoebe declaring that she had “just pulled out four eyelashes” – much to the bemusement of those around her. However, as Maloney points out to , Phoebe can also be seen sipping a cup of coffee behind Monica’s date Paul, and seems to actually be listening to her telling everyone about her eyelashes."

There are plenty of other production gaffes that people have noticed. These little mistakes definitely make for an interesting rewatch for the show. They don't ruin any episodes, per se, but they do highlight just how difficult it is for any production crew to get things perfect while filming.

One of the most interesting blunders that has been pointed out involves a fake Rachel being on set

Fans Totally Missed A Mistake In 'The One With The Sharks'

When filming, stand-ins are often used for scenes. These are just other actors in costume standing in place for the real performer. Well, in one episode of , a stand-in was caught on camera, and someone finally noticed it.

According to "But on this occasion, during the re-watch, we noticed something rather odd about Rachel (Jennifer Aniston) in an episode from the show's ninth season.

Namely that for a few seconds in episode four, The One with the Sharks, Rachel is briefly replaced mid-scene by someone else."

It happens so quickly, but eagle-eyed fans can't miss it now that it's been pointed out.

This also happened with Rachel during "The One With The Mugging", when "Joey joins her in the doorway to talk about the news, before turning to face the rest of the gang – and, bam! Over his shoulder, a woman who is patently not Aniston stands there grinning happily (no doubt glad to have infiltrated the Central Perk gang)," writes .

So, how are some of these errors popping up? Well, switching the show's aspect ratio for streaming seems to be the culprit. Fans are now seeing a wider version of the episodes, meaning the little details that were never seen on TV screens in the '90s are being revealed. Sometimes, it's just an honest production mistake, but some errors are due to the change in aspect ratio.

is still a great show, but we imagine that more mistakes will see the light of day soon enough.