During the beginning scene in which Rose is searching for her daughter, Sharon, she stops for a moment under a bridge. Behind her, in graffiti, is the name "Cheryl," which was the name of the lost girl in the video games. "Cheryl" was changed to "Sharon"...
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In the first section where they are looking for Sharon, The mother s in the tunnel where she drops the teddy bear and starts to run. Pause as she leaves the scene and you will see a basic drawing of pyramid head in the bottom right corner.