Although the episode is entitled "Peggy's New Beau", Dennis says to Mike that "your mother and I have had our romance on slow simmer for 7 years".
When Molly is talking about her and Mike's future, she says that she was the one that had to ask him out. The ending of the pilot, S1 E1, Molly is giving Mike a hard time because he is asking her out "in the middle of a crime scene".
In the closing scene, Vince says the he and Joyce are planning to get married near an active volcano on the island of Kauai. There are no active volcanoes on Kauai, and it is, in fact, the oldest of the main islands and, with the exception of Ni'ihau, the farthest from any volcanic activity.