This "Easter Egg" appears on Hieroglyphs discovered by Indiana Jones inside the Ark’s Chamber.
R2-D2 and C-3PO (Raiders of the Lost Ark, 1981)

This song from a 1986 musical film was the first Oscar-nominated song to contain profanity.
Mean Green Mother from Outer Space in Little Shop of Horrors (1986)

This biopic featured the real lives of these two criminals; one of them having embezzled $800,000 through an insurance company to fund his and his partner's lifestyle before being put behind bars.
Steven Russell and Philip Morris (I Love You Phillip Morris, 2009)

This animated feature film was the first to blend computer animation with hand drawn animation, setting the standard for future computer animated film releases from this entertainment conglomerate.
The Great Mouse Detective (1986), Disney

This low sound used in movie trailers typically produced using brass instruments was first popularized by this film's trailers.
(Name sound and film.)
The BRAAAM from Inception movie trailers