The trivia items below may give away important plot points.
When the warden flips through Andy's bible after his escape, he finds the cut out space where Andy's digging tool was hidden starting in the book of Exodus, which tells the story of Hebrew slaves escaping from Egypt. Exodus literally means "to escape or depart".
The rock wall where Red's "treasure" is buried was built specifically for the film and stood for many years. It was built by hand by the art department months before filming began. This allowed for the alfalfa grass to grow to make it look weathered. Eventually, the wall was sold on eBay, one rock at a time, by the farmer who owned the land it stood on. The tree at the end of the wall stood until it was cleaved in two by a lightning strike in 2011. A portion of its remains now stands, propped up, by the pond on the grounds of the Ohio State Reformatory.
The ambulance that took Boggs away had to be pushed as its engine had died.
Andy and Red escape to Zihuatanejo, a Mexican paradise in the Pacific coastal state of Guerrero. In 1966 it was still a small fishing village which matches how Andy first described it to Red, but has since grown into a large tourist city. The US Virgin Islands stand in for Zihuatanejo in the film.