13 Mistakes In 'Friends' You May Not Have Noticed

Season 1, Episode 19: "The One Where the Monkey Gets Away"

Ross and Rachel stand in Monica's kitchen arguing about how Rachel could have been so careless as to let Marcel the Monkey get away. As the camera pans out to the balcony to show Marcel perched on the railing, we see a new angle of the decor in Monica's apartment. 

By the front door, there is a French painting hung over an end table. Seconds later, when animal control arrives and Rachel goes to open the door, the painting is still there, but the end table has disappeared.

Season 2, Episode 20: "The One Where Old Yeller Dies" 

Joey and Chandler play foosball in their apartment with Monica's boyfriend, Richard. Joey and Chandler are keen on impressing Richard with their maturity because he is "so much cooler" than their dads. 

We see a break in the fourth wall as the camera pans to Richard, who jokes about Chandler's poor foosball skills. Ordinarily, characters don't stand that close to the outside of the set, but Tom Selleck, who plays Richard, gets a little too into character and leans just out of range.

Season 7, Episode 5: "The One with the Engagement Picture"

It's difficult to blame producers for being a bit repetitive when it came to writing Monica and Chandler's engagement announcement in the newspaper, as the ad was only on screen for a couple of seconds. They likely didn't expect anyone to read it all the way through; after all, the point of the announcement was the photo, not the text.

Joey replaces Chandler because Chandler struggles to take a decent photo. The ad is meant to be humorous to those who have the context of the episode, but some eagle-eyed viewers noticed the text wasn't as carefully thought-out as the story. 

In both the "Brien-Torvinen" and "Geller-Bing" announcements, the text begins to repeat itself at the end of the paragraph.

In Season 2, episode 6, "The One with the Baby on the Bus," Ross confirms he is allergic to kiwi, peanuts, and shellfish. Seven seasons later, in Season 9, episode 14, "The One with the Blind Dates," Ross takes home some crab cakes after he's been "stood up" because Joey never sent anyone to meet him at the restaurant. 

Later, while he and Rachel discuss their mutually terrible evenings, Ross is seen eating the crab cakes.

Season 5, Episode 13: "The One with Joey's Bag"

At her grandmother's funeral, Phoebe is passing out 3D glasses and greeting the mourners. After all the friends give their condolences, Phoebe welcomes a man who turns out to be her long-lost father, Frank Buffay.

Frank, having already received a pair of glasses, gets spooked and hands them back to Phoebe before taking off. In her haste and shock, Phoebe turns to her friends to process the news, holding glasses in both hands now. Within seconds, the glasses in her right hand disappear without a trace.

Season 6, Episode 11: "The One with the Apothecary Table"

Joey is dating a dancer named Janine, the woman who also replaced Chandler when he moved in with Monica across the hall. Unfortunately, Janine doesn't like Monica and Chandler, who bust into Joey's  apartment after a double date to confront her.

When Monica and Chandler enter the apartment, the red eraser on the Magna Doodle is on the left side. By the time they leave, however, it's slid over to the right, though the elaborate dinosaur drawing hasn't changed.