According to Hall, "among the missing movies are the world's first feature film [The Story of the Kelly Gang (1906), right], the first Technicolor feature [The Gulf Between (1917)], the first animated feature in both the silent and sound eras [El Apastol (1917) and Peludópolis (1931), respectively], the first werewolf movie [The Werewolf (1913)], the first appearance by Dracula [Drakula halála (1923)], the first kaiju film [King Kong Appears in Edo (1938)], and movies created by Charlie Chaplin [A Woman of the Sea (1926), directed by Josef von Sternberg, produced by Chaplin], Orson Welles [the 40-minute Too Much Johnson (1938)], Woody Allen [the alternate version of September (1987)], Sergei Eisenstein [the unfinished Bezhin Meadow (1937)], Ed Wood [the XXX-rated Take It Out in Trade (1970)], Oscar Micheaux [the interethnic drama The Betrayal (1948)] and Martin Scorsese [the original shoot-out sequence from Taxi Driver]."
The vast majority -- 38 -- of the films listed are American productions. Many of those are shorts; others, such as the Australian-made The Story of the Kelly Gang, survive in bits and pieces; and others yet, e.g., James Dean's screen test for Oklahoma and an alternate shoot-out sequence from Taxi Driver, are movie sequences, not movies.
I'm not sure how Hall found out about those titles -- there are many I'd never heard of -- or what his criterion was for his 50 choices, but I did notice that missing from his list are several that I would have mentioned. For instance:
- Rex Ingram's Trifling Women (1922) and Where the Pavement Ends (1923), two well-regarded and quite successful 1920s melodramas, both starring Ramon Novarro, and directed by one of the top Hollywood talents of the silent era;
- The Miracle Man (1919), which provided Lon Chaney with his first major role in a highly successful motion picture;
- The Noose (1927), for which Richard Barthelmess was nominated for a best actor Academy Award;
- Ernst Lubitsch's The Patriot (1928), a period drama starring Emil Jannings, Florence Vidor, and Lewis Stone that was "considered" for several Academy Awards covering the period 1928-29 (there were no official nominations that year).
Of those films in Hall's list that I'd never even dreamed existed, I must admit that the one that most aroused my curiosity was Him (1974, USA), described as an "X-rated film about a gay man's homoerotic obsession with the New Testament" that was detailed in the 1980 book The Golden Turkey Awards.
If Him is ever found, it'd make a great double-bill with Cecil B. DeMille's kinky The Sign of the Cross. Here's hoping.