Continuity mistake: You see Phil take the coffee mug from the roof of the car and then he goes inside the car. A few seconds later it's back on top, then a few seconds after that it's gone again. (00:15:30)
Continuity mistake: When Cam is talking to Lily, the doorknob looks like it's loose, and in the next shot it is fixed. (00:19:49)
Answer: Mitch is upset that his dad doesn't seem to support his getting married. When they talk about Jay's friends not coming to the wedding, Jay makes it seem like Mitch wouldn't want them to come anyways. Mitch sees it as it's actually that Jay doesn't want to invite his friends to his gay son's wedding because he's embarrassed and uncomfortable about having a gay son. Essentially Mitch sees it as if he was marrying a woman, Jay would be willing so spend money on the wedding, host it at the club, and invite all his friends to it.
Bishop73