Corrected entry: When Frank (the thunderbird) releases the amnesia liquid over New York, every No-Maj's mind is wiped, including those inside buildings. If that were to happen, there would not have been any time for a goodbye with Jacob, as the rain would have wiped him the second he was above ground. If the spell had given time for a goodbye, everyone inside buildings should remember the Obscurus attack and the spell would be pointless.
Phixius
24th Apr 2017
Fantastic Beasts and Where to Find Them (2016)
23rd Nov 2016
Fantastic Beasts and Where to Find Them (2016)
Corrected entry: When Newt chases one of his creatures through Central Park, the park is heavily covered in snow and people are ice skating on a frozen pond. At any other time directly before or immediately after this scene and throughout the movie, there is virtually no snow anywhere in comparison to what's in the park, and people are dressed for moderate weather.
Correction: It struck me as a bit of a reach when I watched it, but the film establishes the manner in which the spell affected people indoors by showing them all interacting with water in some way (drinking it, showering in it, etc). Since Jacob had not yet been directly exposed to water, his memory remained.
Phixius ★