Goofs

When Monica tries to make up for not bringing original hand made gift for Chandler, she cooks for him 3 days in a row (as said by her during the meal of macaroni and cheese) but later in a scene they say that this night is their Valentine's night (which actually was 3 days earlier).

When Joey is complaining to Monica and Chandler about Karls lack of acting skills, Karl sticks his head in the door to ask if he can have a piece of the cake Monica made. But he couldn't have known about the cake as he came in before Monica had a chance to take it out of the oven.

Chandler takes a hanger from the closet and bends the bottom of it into an acute angle, a quick camera angle change and the bottom of the hanger is no at an obtuse angle.

Ross explains to Chandler that his Saturn V Rocket model is from the Apollo 8 mission and that Apollo 8 did not land on the moon but instead orbited the moon twice and returned safely to earth. In fact, Apollo 8 orbited the moon a total of ten times, not two.

Ross' model rocket couldn't have been from Apollo 8. Apollo 8 used a Saturn V booster which has three stages, Ross' model is a 2-stage rocket which would make it a Saturn IB. It was designed strictly for Earth orbit missions and only flew with a crew once, Apollo 7, during the lunar landings build-up. It later flew for missions to Skylab.

Unagi is not a term used in martial arts, in any form at all. The concept that Ross is speaking of is actually Zanshin. Unagi is eel.

As Carl gets a soda from the fridge, Chandler can be seen trying not to laugh.

After Monica forgets to make Chandler a Valentine's present they both head to the bedroom as part of her apology. In the next scene they leave the bedroom when the cake timer sounds, but it is never mentioned when Monica left the bedroom to make the cake.

The clinic nurse tells Joey the next study is a twin study. When Joey states it's worth $2,000 the nurse says sorry. The nurse never asked if Joey was a twin and Joey never said he wasn't before the nurse apologized.