en.wikipedia.org/wiki/Once_Upon_a_Time_in_America

The statement misidentifies the origin of “Amapola.” Contemporary sheet-music and catalog records describe it as a song, not an opera excerpt.

• The Mississippi State University sheet-music record for “Amapola” lists Joseph M. Lacalle as composer and lyricist, gives a 1924 publication date, and classifies it under Music Genre: Popular with performance medium piano; voice.
• IMSLP likewise catalogs Amapola (Lacalle, Joseph M.) as a 1920 composition in the genre category Songs, for voice and piano.

So while Amapola has often been performed by operatic singers, it did not originate as an opera piece.

Box-office references do not support a $5.5M domestic total for the original U.S./Canada run.

• Box Office Mojo lists the film’s Domestic gross as $5,321,508.
• The Numbers also lists Domestic Box Office $5,321,508, and its week-by-week chart ends at the same total.

Because the claim is specifically about the domestic theatrical run in the U.S. and Canadian markets, the best-supported figure is $5,321,508 (about $5.32M), not $5.5M. Some sources list slightly different worldwide totals because of later re-releases, but that does not change the original domestic run total.