There is also the MGM Jerome Kern musical biopic "Till The Clouds Roll By" in which, early in his career it looks like he is going to get the big break he needs, befriended by Charles Frohman etc, goes to pier to bid Frohman farewell, cut to Lusitania poster, cut to next scene of Jerome (Robert Walker) looking all depressed for obvious reasons. It's an awful movie on every level except for the music.
Similarly awful, and probably the featuring the same prop newspaper previously mentioned, is the MGM musical in which Gene Kelly plays a "heel" who slams his hand inside of a steamer trunk to avoid military service (I think it is For Me And My Gal) in an earlier sequence there is the cliche "Lusitania Torpedoed" newspaper cover insert shot.
There are some stills from "Lest We Forget" over at Ren's site, which I donated, but only one shows the sinking sequence.
Kenneth Brownlow's Hollywood series, done for British television, has been on video for about 20 years and can be found for rental with relative ease. The Lusitania clip appears in the "Hollywood Goes To War" episode, but less than a minute is used. Just enough to leave one curious about the rest of the movie. If The Library of Congress has it in their film archive, being that it is pre-1923, they WILL copy it for you but it will cost you quite a bit.
Lest We Forget is a mostly "lost" film. What survives is one deteriorated reel.The most common still from the movie is the one showing her, Edith Cavell style, refusing to be blindfolded before her execution. I tend to suspect that there is a last minute rescue by her "wounded countryman" boyfriend.