Trivia: At the beginning of the film, when Billy is late for work, you see two films playing at the movie theater: "A Boy's Life" and "Watch the Skies." The former was the original title for "E.T." and the latter was the original title for a proposed sequel to "Close Encounters of the Third Kind." Two films directed by executive producer Steven Spielberg.
Trivia: When the first nasty gremlin is scrabbling around the darkened schoolroom, at one point we see a scaly green hand reach up and grab an apple off the teacher's desk; we hear munching; and then the gremlin says something and throws the apple away. If you're not Jewish, and you saw this film with someone who is, they may have laughed, and you may not have known why. What the gremlin says is "Trayf.", which is a Yiddish word meaning "not kosher" - i.e., anything which doesn't meet Jewish dietary laws (pork, etc.).
Trivia: Reportedly, director Joe Dante attended an early test screening and was waiting outside the theater to see what the audience reaction was. Midway through, an angry mother pulling her young daughter behind her barged out of the theater and began to scream at him. The mother felt the film was too violent for children and thought it had frightened her daughter, and chewed Dante out for several minutes. After she was finished yelling at him, she realized that her daughter had gone missing. It was only after the movie was over that she and Dante discovered that the young daughter was actually enthralled by the film, and had snuck back in the theater while he mother confronted Dante, hiding beneath some seats so she could watch the rest of the movie. Dante found the mother's over-reaction so amusing, he included a brief reference to it in the sequel, during the "Hulk Hogan" scene.