Heather O'Rourke's mother and uncle recently auctioned off some of her TV and movie memorabilia. One of the items was Heather's copy of the script of this episode.
Heather (Heather O'Rourke) says she cannot read. In real life, Heather learned to read at age 5 (she was 7 at the time this episode was filmed).
Heather' O' Rourke's "he's here" remark announcing Fonzie's arrival is similar to her "they're here" remark she made in her 1982 Poltergiest movie announcing the arrival of the poltergeist.