When Kramer and Elaine discuss sending her a fax, the level in Kramer's juice bottle suddenly drops without him drinking any.
Phone numbers are changed at the phone company, there is no need for a home visit and new equipment to be installed.
There's no way the little boy would know where to send the paramedics.
Just prior to storming out of Jerry's (Jerry Seinfeld) apartment, George (Jason Alexander) says, "Say goodbye to Koko," and Jerry responds, "Goodbye Koko." Kramer then enters the apartment & appears to say, "Goodbye Koko," however the voice is clearly dubbed and is not Michael Richards'.
When Jerry and Elaine are playing Battleship Elaine tells Jerry he hit her ship but Jerry puts a white peg in the board rather than a red one.