One can find some fragmentation grenades in a green trash can on the left of the wooden bridge exiting Sanctuary Hills to the east. This is similar to Fallout 3 where, in Springvale close to the exit of Vault 101, one can find frag grenades in a blue mailbox.
Sanctuary Hills is referred to as just "Sanctuary" on the official location marker in the game.
There is a random encounter in which one can come across feral ghouls with the names of some of the pre-War inhabitants of Sanctuary Hills. This encounter is repeatable, even if the ghouls are killed.
Upon returning and "discovering" Sanctuary Hills for the first time, an acoustic echo from It's All Over But the Crying plays and slowly fades out.
The white picket fences found around the outside of the houses count towards the item limit. They can be scrapped, or stored if the appropriate Picket Fences magazine is found if this becomes a problem.
When Sanctuary Hills is under attack, assaults can come in via the southbridge, via the path north to Vault 111 and even from the east.
After exploring the neighborhood with Codsworth, he tells the Sole Survivor the directions to Concord. In his directions, he mentions the footbridge to the south which was used for both vehicle and foot traffic before the war. Preston Garvey states the footbridge dates back to the American Revolutionary War, therefore over 600 years old.
The Concord water tower which can be seen in pre-War Sanctuary uses the post-War model.
The chem dealers house in pre-War Sanctuary contains two large, blue shipping containers.
The Chryslus Cherry Bomb found in the driveway immediately to the right of the path leading to Vault 111 can be found rotated 180 degrees after leaving the Vault.
Sanctuary Hills appears in the ending slides, though as a separate layout indicated by the house storing the workshop is in complete ruin.
Jun Long, Marcy Long, Preston Garvey, and Sturges will frequently leave assigned posts to hammer on the workshop house. This has no impact on their assigned role (food will be produced, security rating will be maintained, etc.), but can be an issue if they're assigned to a strategic guard post.
Sanctuary Hills can become a target for the Nuka-World raiders to take over.
The pre-War version of Sanctuary Hills is not truly changed by the nukes in the game files; instead, Sanctuary Hills (pre-War) is a separate location, and the player character is moved to the standard game map after the cryo freezing scene in Vault 111. The original Sanctuary Hills may be accessed by using the console command coc PreWarSanctuaryExt01.
The acoustic echo of It's All Over But the Crying, is possibly a reference to the original Fallout and Fallout 3, as other songs (Maybe and I Don't Want to Set the World on Fire) from the same band are played at the beginning of the two games' introductions, before the series' iconic "War... War never changes" speeches.
↑Fallout 4 Vault Dweller's Survival Guide Collector's Edition p. 258: "[1.02] SANCTUARY Growing from the ruins of Sanctuary Hills, the prewar neighborhood your family used to call home, is a new settlement, a beacon of hope for the downtrodden and the new base of operations for the Minutemen." (Fallout 4 Vault Dweller's Survival Guide Map)