Continuity mistake: Frasier (and later the others) come back to his apartment to avoid the rain - they shake off umbrellas, and we even hear the storm at the very start of the scene. However there's no rain on the balcony - can't be covered, as we see in "Call Me Irresponsible" during the obligatory sex scene that when it's raining the balcony gets soaked.
Audio problem: Just before Frasier opens the door to get his paper, he says "I'll get him for this and his little dog too". However, his mouth moves when he says "I'll get him for this and his...", but his mouth doesn't move when he says "...little dog too". (00:02:40)