The physical film is clearly from two sources, most likely some film shot by the amateur creator and some purchased material that he edited together with his own footage. The Gilbert family retains photograph albums from the same trip, also containing photographs by the Gilberts along with purchased prints and postcards.

Did the cruise ship provide film sequences to its passengers for purchase?

Was the footage bought in shops at the ports of call?

Have you seen similar examples?

Do you know of 16mm film bought on other ships?

Were the film labs on ships?

Does it matter that the film is compiled from different sources?

Are intertitles important?

How do you imagine Gilbert's audience?