(at around 17 mins) When the adult Beverly visits her old home, she sees three names on the buzzers. Two of the names are historical murderers, Starkweather and Burke. Starkweather refers to Charles Starkweather, a young man who killed his girlfriend's family when they attempted to prevent them from being together, then took his girlfriend on a murderous spree in the 1950's American Midwest. Burke refers to William Burke, a man who teamed with William Hare, who first rob graves to provide corpses for medical study in 1820's Scotland, then turned to murdering their lodgers to earn more money.
(at around 20 secs) When adult Bill visits Georgie's grave, one of the other headstones is that of Peter Terranova. This indicates that the stone is a re-used prop from Wiseguy (1987) in which Peter Terranova is the murdered brother of lead character Vinnie Terranova.
(at around 2 mins) Bill is the author of a horror novel titled "The Glowing". This is a reference to Stephen King's The Shining (1980).
(at around 13 mins) When the balloon appears in Ben's taxi, John Ritter was turning it with his finger, off-camera.
(at around 6 mins) In the library scene when older Richie sits down holding his water you can see Tim Curry in a background role as the man sitting behind him to the Richie's right shoulder.