The first time Joey is shown with the Porsche, the car windows were closed. The second time Joey is shown with the Porsche, the windows were open. When the car owner comes back, he gets in the car and does not mention anything about Joey having opened the windows. So, either the windows should have been open or closed both times Joey was shown with the car, or the owner probably should have been upset that Joey opened them because that probably would have meant that Joey was in the car and perhaps even drove it.
When Ross grabs the paper from the court reporter, he reads the paper and yells "Stop typing 'Stop typing'!" However, the court reporter was a stenographer using a stenotype machine, which types in a special shorthand, and wouldn't be legible to anyone not trained in stenography.
When baby Leslie is shown playing in the drawer, she is not wearing a diaper and you can clearly see that "she" has a penis.
When Phoebe, Chandler, and Monica are changing the triplets diapers, Chandler picks up a girl baby to give to Monica and the girl baby clearly has boy parts.
One of the crew members leg can be seen when Phoebe is looking for the baby.
At the beginning of the episode, Phoebe asks Monica and Chandler if they would like to help her take care of three puppies. Both of them agree, however it is later revealed that Chandler hates dogs (including puppies).
While putting the diaper on the baby chandler is seen waving his hand to the crew.