In The One With Monica and Chandler's Wedding, Part 1, after Joey reveals he's in a film about World War I, the women don't know who it was the US fought in it. Yet at the end of this episode Phoebe apparently has past-life memories of being a WWI nurse, so she should know.
The 'flashback' scenes are wonderfully executed. Chandler with 80s hairstyle looks scarily like Paul Merton ("Polar bears over Wolverhampton? Could I BE any more surreal?!")
Thankfully, this one is not a clip show, just an "original flashback" show. They usually do not cause frustration and anger for me the way clip shows do. And this one was actually not too bad, as I already said on the page for the eighth season ep. "The One With The Rumor".
The best part was probably Joey with the huge turkey stuck on his head, a la Mr. Bean's Christmas Special. That scene apparently had to be filmed several times because the involved actors kept cracking up. That I can understand!
Loved the bits of Phoebe's past lives, where she was a nurse in the U.S. Civil War and the First World War.
She gets in an explosion, and her left arm just falls off, and the blood spurts out like it comes from a tube. And Past Pheebs just acts like it's a minor annoyance.
Clearly, these bits were inspired by Monty Python.