Blooper

While talking with Angela in the restaurant restroom, Monica says, "My brother never even told me when he lost his virginity." In the previous episode, The One with George Stephanopoulos (1994), Ross says, "Today's the day Carol and I first consummated our physical relationship." Joey replies, "You told your sister that?" to which Ross replies, "Believe me, I told everyone!" Monica also indicates she remembered the anniversary on her own, saying she hopes Ross wouldn't remember the date, indicating strong familiarity with it.

While it's not the producers' fault if the network runs the episodes in the wrong sequence, this one provides definitive proof of that happening: Monica tells Angela about the Underdog balloon that broke free over the city, something which happens chronologically only four episodes onward in The One Where Underdog Gets Away (1994).

In The One with the East German laundry detergent, Rachel is not able to defend herself from a mean woman in the Launderama, so Ross helps her out and she says "I can't even send back soup". However, In the The One With The Flashback, which is set back when Rachel just got engaged to Barry, she is sitting in a bar with her friends and returns their drinks to the waitress since she did not bring the right ones.

In the laundry room, "clothes" is misspelled "cloths" on a sign.

Rachel tells Ross that she can't even send back soup, but Rachel sends back a drink in a flashback in The One with the Flashback (1996). Chronologically that would have been a year earlier. However, Rachel's personality changed after she moved in with Monica and began working. After working as a waitress herself, she might have changed her demeanor toward waitstaff and not made complaints.

In the restaurant, Joey shares/hands over a chicken wing to Angela to impress her but in The One with the Birth Mother (2004) Joey says that "Joey doesn't share food" with anyone. However, he enjoys the way she eats so much that he has either made an exception or they were ordered just for this reason, as indicated by him ordering another plate.

When Janice comes into the coffee shop to talk to Chandler, she brings a shopping bag which she sets by the couch. But when she gets back from the restroom and Phoebe breaks up with her for Chandler, she leaves the coffee shop without getting her bag from in front of the couch. Presumably though , the only thing in the bag were the socks she bought for Chandler so the bag is his now.

Chandler mentions that "Ugly Naked Guy" is laying kitchen tiles. However, when Ross moves into the apartment, it's shown that the kitchen in that apartment cannot be seen from Monica's apartment.

As Ross and Rachel are taking laundry from the washing machine, the clothes are clearly dry.

In the first scene at the laundromat, there is the sound of a front load washer ending its spin cycle. None of the shots show any front-load machines. A top-load machine would make a very different sound at the end of its spin cycle. The only time a top-loader would make the same sound is if its lid was opened.

Additionally, there are signs that say "use our giant washer." None of the shots show a large washer extractor.

When the "Horrible Woman" is pushing Rachel in the laundry cart, you can make out a microphone box and wire under her shirt

The mean woman at the laundromat didn't bring any detergent with her, nor did she buy any from the vending machine on the back wall. She's putting in quarters and getting ready to start a load without detergent when Ross confronts her and makes her back down.