The story about the ships beneath San Francisco is true. Hundreds of ships were abandoned by hopeful gold miners. One fellow set up a salvage company, hauling some of them ashore and leaving some afloat to be used as storage units, boarding houses and even a jail and a church. The city needed to expand its acreage so that they could expand the harbor so they sold water lots. People would take an abandoned boat, scuttle it, and then claim the lot. To keep it they had to fill in the water by dumping rock, sand, and dirt. As it settled, much of it served to support the ships and many of the hulls were preserved largely intact. Decades later as underground utilities were being installed the ships were discovered. So far they have found some 500 of them. Much of downtown San Francisco was built on top of them,
It is a frequently asked question whether Harrison Ford dubbed the voice of his character's younger self. The answer is no; director Lee Toland Krieger found Anthony Ingruber impressions of Ford on his YouTube channel and sent him an email asking to try out for this film. Ingruber said he has been doing his Ford impression since he was 15.
In order to create a sense of authenticity for shots set in the 1930s, 1940s, and 1950s, filmmakers used anamorphic lenses and limited the use of steadicams.
Adaline's birthday on the fake IDs she picks up at the beginning of the film is actually the same birthday as Blake Lively's, 25th August, with only one year difference (1986 in the film, Lively was born in 1987)
J. Mills Goodloe's original screenplay featured New York as the setting for the film, but the writers later changed the location to San Francisco because they thought it had a more appropriate ambiance for the film.