Things You Didn't Know about F.R.I.E.N.D.S

120)

In the episode where Monica Buys her wedding gown she is seen wearing one dress in the botique.

When she goes to get the dress on sale she shows Phoebe and Rachel a picture of a different dress to find.

Then she fights over a completely different dress, but when the dress is shown later in her apartment it is the original dress from the botique.