When Rachel begins to look for her ring under the couch, Monica mentions eating ice cream while holding a spray bottle and towel. The bottle disappears then reappears in her hand before the conversation is concluded.
Just as Ross turns around when he hears the baby's heartbeat, the doctor lifts the device off Carol's stomach, yet the heartbeat continues to be heard.
When everyone is starting to look for Rachel's engagement ring, Chandler is in the living room on a chair. As Monica says, "Easy, Rach, we'll find it, WON'T WE?", Chandler jumps up off the chair. The camera cuts back to Monica, and now Chandler is in the kitchen by the fridge.
At the gynecologist's office, Ross picks up a piece of medical equipment and nervously manipulates it to mimic a duck quaking. Carol (incorrectly) says, "Ross, that opens my cervix." The device, called a speculum, is used to dilate an orifice in the body to allow inspection. In this case, it would open the vaginal canal to allow inspection of the cervix.
Ross is working on a display of early humans. However, he is a paleontologist, and working with early humans would be the job of an anthropologist.
Ross and Carol are already divorced before the show starts, yet she still isn't showing her pregnancy, which means they must have had sex after the divorce.
The characters put their hands in the lasagna but none of them act like it is hot.
Barry is referred to as Dr. Farber from here on out. When Rachel first ran out on her wedding and told everyone about it, she told them his name was Barry Finkel.