Ok first in 407 don't know the exact title but it's TOW Chandler kisses Kathy... Ross says that it will be the firs time he'll play his music in public. Didn't he have a band with Chandler as a lead singer and is on eppy in the 6th season Ross says to Rachel that he played he an "Interplanetary blah blah blah sth" which seems to be one of his songs. I know it is ni TOW What could have happenbut still Ross is talking about the things that actually happen.... And in 306 TOW Flashback when Chandler meets Rachel in the pub they act as if they don't know each other, but in TOW All Thanksgivings there are scenes where Ch and R meet (two years in a row). I don't think Chandler would forget a girl like Rachel in 4 years time (he desperately needed girls in 88-92 period), it's more likely that Rachel would forget him.... but still it is a clear mistake for me...
best wishes Lormar