Some of them are simply easter eggs; others are actually story/series-relevant.
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o1. CONVENIENCE STORE 8

One of the first we find is in Wood Side Apartments. In Room 217, James finds the handgun in a shopping cart. The shopping cart in the original game is for Long's Drugstore (as I recall). Here, though, it's Convenience 8, the convenience store Harry can (optionally) enter on Bachman Rd. and Finney St., where an Air Screamer is lounging on a trash can — and where he can find the Channeling Stone on New Game+.
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o2. PREVIOUS LOCATIONS in OLD and NEW SILENT HILL

On a board in town, you can find several posters for locations specific to SILENT HILL: Including Lakeside Amusement Park, the Lighthouse, and Balkan Church.
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o3. GREEN PHARMACY

James can access Green Pharmacy via Saul St. Apartments on . . . Saul St. It's a small shop with a receipt on the counter for some fictional medications. On the other side of Toluca Lake, near the corner of Koontz St. and Canyon St., up the block from Alchemilla Hospital, is also Green Pharmacy. Harry can't do anything here, it's just a nice little nod — same tree logo and everything!
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o4. ALCHEMILLA HOSPITAL PAMPHLETS

Speaking of Alchemilla Hospital! There's a brochure for it tucked away in some of the pamphlet holders in Brookhaven Hospital, one of which is for the northside's hospital, where Dr. Michael Kaufmann was the previous director.
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o5. DR. MICHAEL KAUFMANN and AGLAOPHOTIS


Speaking of Dr. Michael Kaufmann! In a pamphlet holder in Brookhaven Hospital is a book called Life and Reality, along with a handout about . . . Aglaophotis!? Weird! That same medical book can also be found hidden in one of the bookshelves around the hospital. Its author? Dr. Michael Kaufmann. Who knew he was a published author?
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o6. CARL JUNG & the MODEL of the PSYCHE

Speaking of published authors! Carl Jung makes several "appearances" in the Silent Hill series. Here again in Brookhaven Hospital is his "model of the psyche." Interestingly, though, is that deep in the middle of the self is a hidden Virun VII Crest/Seal of Metatron. Does that mean the Seal of Metatron encapsulates the self? Hmmm. . . .
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o7. THE VIRUN VII CREST/SEAL of METATRON

Speaking of the Seal of Metatron! Opposite the wall in the "ritual" prison cell room with the sigil of the waxing and waning moon is this drawing of a pentagram. Written within the outer circles are the same symbols seen on the Seal of Metatron.
*Note: The Seal of Metatron is also, still, depicted on the floor during the duo Pyramid Head fight, even though its inclusion was originally called "a mistake" by Masahiro Ito. Funny that not only did they keep the sigils, but they added more to SILENT HILL 2: REMAKE.
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o8. THE GILLESPIE HOUSE

In Lakeview Hotel's grand staircase, several paintings are on its walls at which to marvel. One of them is none other than the Olson—er, I mean Gillespie House. What's peculiar here is that according to the original, the fire which destroyed the house also destroyed six other houses. Yet a major point of contention was how — because the Gillespie House is clearly in the middle of a field with no surrounding houses. Well, that didn't change and it's still here in the middle of a field. Unless this actually is a depiction of the Olson House in Cushing, Maine, not far from where Silent Hill is set. Except . . .
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o9. . . . AND THE FIRE THAT DESTROYED IT

A newspaper headline is posted outside of Groovy Music. The headline reads:
Gillespie house fire — arson or accident?
New evidence after years
Well [expletive deleted] me. That's kinda wild, right? This has quite a few implications, even if they are fairly open-ended.
The question of whether Dahlia intentionally set Alessa ablaze has been a point of contention among fans for decades now. So while this doesn't answer that question, it at least provides some context — that the developers are acknowledging it (and the fans, again).
It's something that will definitely be nice to see in a (potential) future remake of SILENT HILL, as well as how the Gillespie fire is handled.
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Speaking of the Gillespie fire!
j/k
That's what I've got so far. If you know of any I've missed I'll happily include it in this post.
Thanks for reading.
XXXoxo,
The Adversary