When Luntz/Harry walks past two teenage girls, there is a cardboard sign nearby saying "Time Enough at Last" and a drawing of a clock. This refers to The Twilight Zone: Time Enough at Last (1959), an episode of the original 'Twilight Zone' series.
The rotary phone in Harry and Monica's apartment is identical to the toy phone in the original Twilight Zone episode The Twilight Zone: Long Distance Call (1961).