At 12:47 refers to "my fortress of solitude" which is Superman's hideout.
Postman refers to Z's as "Walkers." First time in series this is said.
At 05:15 new character Wally Becker says "Come with me if you want to live." which is a tagline from the original "Terminator".
At 5:27 Doc says "Neither rain nor sleet nor zombie hordes..." which is a paraphrase of "Neither rain nor sleet nor darkest night shall stay these couriers from the swift completion of their appointed rounds".