While his wife Joanne is hiding under the covers, Jack Morrison tells her that he has compiled a list of thirtysomething guests for their housewarming party when they are finally able to move into their new house. This is an in-joke referring to the fact that Patricia Wettig (Joanne) left St. Elsewhere (1982) after she was cast as Nancy Weston in Thirtysomething (1987).
As Dr. Craig is reviewing the case of Mr. Spooner as an artificial heart recipient, he says life after the surgery won't mean "a day at the races or a night at the opera". Craig puns the names of two Marx Brothers films (1937 and 1935, respectively).
When checking over the artificial heart, Dr. Craig asks, "What was that pop, Werner?", a possible reference to Pop Warner.
Other Marx Brothers reference, Soup to Nuts and Fiscus turning Morrisons picture into Groucho