Continuity mistake: Jerry was forced to take the phone call thanks to Kramer. He is holding the receiver in a different way between shots - look at the position of the index, on the microphone in the second shot. (00:03:50)
Continuity mistake: In the hallway scene at the beginning, Jerry is holding a magazine. When the man comes out of the elevator, he is holding the magazine The Opposite way - easy to tell because of the Marlboro ad in the back, now flipped. (00:01:55)
Continuity mistake: In Jerry's apartment at the beginning, Kramer hands Jerry the telephone. Jerry takes it with his right hand, but in the wide angle he is holding it in the left hand. (00:03:40)
Answer: The name is Delores. He shouts that name at the end of the episode. Then in a later episode, "The Foundation", he runs into her. And he repeatedly calls her Delores.