I seem to recall the human character- Elliott ( we never learn his last name but it is not Ness) watches the classic science-fiction film This Island Earth on TV ( a dumb plot device- screen-within a screen) that has been used a bit much.
ET stood for Extra-Terrestrial in the movie ET.
et
The movie came out in 1982.
An Extra Terrestrial
The family dog in ET The Extra-Terrestrial is named "Harvey."
If you mean "E.T. the Extra-Terrestrial" (1982), there is no sequel.
extra terrestrial
Extra terrestrial
et
Extra-terrestrial
Extra-Terrestrial - ET.
its Harvey.