Visible crew/equipment: When Martin is fighting the "puppy" at the door, you can see a crew member's hand pushing the doorknob open to portray the puppy is trying to get back into the room.
Continuity mistake: In the 1991 flashback, Jamie is already engaged to Paul and is shown with long hair. However, in the 'Cold Feet' episode, Jamie is shown with short hair. Since the 'Cold Feet' episode was set in February of '91 and the flashback from this episode was set in late March or April of '91, these two episodes don't match up.
Desperately Seeking Samantha - S6-E5
Continuity mistake: As Ernie the cook is exiting the restaurant kitchen with full plates of food in each hand, Samantha enthusiastically surprises him and he immediately hugs her, but his hands are now empty. (00:17:30)