During the kitchen conversation about using the name Ross for one of Phoebe's babies, a very large piece of white lint appears in the center of the gray section of Ross' shirt; then disappears and reappears several times.
When Joshua's father asks if they (Joshua and Rachel) have eaten, the mask on the table in the corner behind Joshua has red lit eyes. The next time they show the same angle, the eyes are dark. The next time, they are red again.
When Rachel is sitting on the couch in her nightie practicing how to seduce Joshua, her legs are crossed. When he comes out of the kitchen with his parents, in three quick shots her legs go from being crossed, to uncrossed, to crossed again.
Ross refers to the comic book "The Incredible Hulk #72", but
no such comic existed at this time. "The Incredible Hulk" was canceled at #6; the Hulk then appeared as a feature in "Tales to Astonish" until he took over the title in 1968 and it was renamed "The Incredible Hulk" with #102. There were no issues numbered #7-101 until the title began renumbering with #1 in 1999, a year after this episode aired.