Corrected entry: The wedding is threatened because Ross, Emily, and Monica discover that the location has been torn down a few days early. However, when one plans an event, especially a wedding, one puts down a deposit to hold the location, signs a contract, and has all of that in writing. The church would not have allowed the tear-down to happen early as they'd be in breach of contract for accepting money and then allowing the church to be torn down before the wedding. And if they had broken the contract, Monica would have been screaming about it and demanding a refund.
Corrected entry: In the episode 'TOW All The Wedding Dresses', Monica picks up Emily's wedding gown for her at the bridal shop and then wears it for most of the episode. However, in the episode 'TOW Ross's Wedding', Emily is seen wearing a completely different dress.
Corrected entry: Rachel and Phoebe are in the girls apartment and Phoebe tells Rachel to bring her some tepid water, a piece of chocolate and some photos of Ross. In one shot she is holding the water and chocolate, but in the next, a box of photos appears as well.