Continuity: It is odd that Ross's son, Ben, would not be in or at least at his father's wedding. He was in Carol and Susan's wedding in "The One with the Lesbian Wedding."
Note: It's not that unusual since Ben at age 3 would have little idea of what was happening. Moreover, Ben would need constant care, perhaps requiring that Carol come along, as well. His presence at Carol and Susan's wedding, on the other hand, was a relatively simple matter, logistically--even saved them hiring a babysitter.