Dwight paints the manager's office black and says "it's like outer space without the stars, it's so black". This is almost verbatim Nigel Tufnel's reaction to Spinal Tap's all-black album cover.
Pam's secret note to Jim: "Don't forget us when you're famous!" and Jim's trip back to the office to see her are a subtle mirroring of a scene in the Christmas special, where Dawn Tinsley (Pam's analogue) finds a touching note from Tim in her bag and rushes back to the Christmas party to kiss him.