The day of the week printed on the wedding invitation is Wednesday, but the date printed after it was actually a Sunday.
At the 0:30:31 mark Kenneth says "You'd make somebody a good wife", but Gene Raymond is biting into a sandwich and not speaking. Plus, the line was quite obviously dubbed in by someone else, it's not Gene Raymond's voice.
The flashback to the party before John and Moonyean's wedding includes an important scene in the garden involving only Moonyean and Jeremy. The framing device of the flashback is John telling Kathleen what happened back then. However, since Moonyean died and Jeremy disappeared forever the next day, there was no way for John to know what happened in the garden scene that he apparently relates to Kathleen.