Traditionally, guys called "Red" are redheads (this was the case in the novella). Initial casting calls had that in mind. The role is played by Morgan Freeman, who would not pick up that nickname naturally but owns the role anyway. It's explained in the film (though not in the novella), that Red's nickname comes from his name, Ellis Redding.
This is referenced in the film when Andy asks him why he's called Red. The reply "maybe because I'm Irish" is a reference to the Red character in the original novel, who was both red headed and Irish.
For that matter, Tim Robbins as Andy qualifies. In the novella Red describes him as a "small, neat little man". Tim Robbins is 6'5", but he nails the role.
Acclaimed Flop: The film had a lukewarm box office reception (mainly due to Invisible Advertising) despite receiving favorable reviews from critics. Averted once it found its audience on home video - it sailed past Cult Classic and became one of the most popular and beloved films of all time.
A sequence where the convicts find Jake (Brooks's pet crow) dead in a field sometime after Brooks has left the prison, and the convicts give Jake a funeral and burial. This deletion ends up providing a subtle thematic shift; as scripted, both Brooks and Jake represent the dangers of institutionalization, but as depicted on screen, Jake ends up foreshadowing Andy's successful escape in the climax of the film, not to mention contrasting Red's successful bid for freedom.
Tommy's young wife visiting him, their conversations providing a more vivid illustration into why Tommy decides to turn his life around and approaches Andy to work on getting his GED.
After Andy's escape, an unfortunate guard is sent into his tunnel to see where it leads, and when he sees the sewage pipe broken into and smells the overwhelming odor of shit, he vomits - loudly. Red hears this happen from his own cell and cracks up laughing. He's sent to solitary confinement for two weeks... where he continues laughing, thus learning for himself what Andy (in the aftermath of the loudspeaker incident) had meant about "easy time" in the hole.
Red's feelings on the 1960s after he is paroled, as well as a panic attack in the grocery store that sends him running for a bathroom cubicle that calms him down because it reminds him of his cell - thus making his choice to find the tree and rock wall more meaningful, because it runs counter to Brooks's choice.
Executive Veto: Frank Darabont originally wanted to end the film with Red on the bus traveling to Mexico in the hope of reuniting with Andy. Producer Liz Glotzer insisted that he shoot a scene of them actually reuniting, which ended up being included in the final cut after test audiences loved it.
Font Anachronism: The rubber stamp used by the parole hearings people in 1947 prints in the Helvetica font, a decade too soon.
In Memoriam: The movie is dedicated to Allen Greene, a literary agent and close friend of Frank Darabont who died of AIDS during production.
Method Acting: Tim Robbins asked to be locked in solitary for a while to get a feel for it. He knew his experience wouldn't be the same because it was voluntary.
Playing Against Type: Oddly enough, Morgan Freeman as Red counts, even though it's one of Freeman's best-known roles. Though Red is a generally good-natured guy, he's a far cry from the kindly old authority figures and humble mentors that Freeman is best known for playing. Instead, he's a cynical murderer who deeply regrets the mistakes of his past, and ultimately has his life saved by following someone else's example.
Real-Life Relative: The mugshots of a young-looking Red that are attached to his parole papers are actually pictures of Morgan Freeman's younger son, Alfonso Freeman. Alfonso also cameos as the con who shouts "Fresh fish! Fresh fish today! We're reeling 'em in!"
Shrug of God: Frank Darabont has admitted that the Christian interpretations of Andy Dufresne (a saintly figure who is unjustly accused, brings hope and goodness to sinners and the downtrodden, and is cast down into "Hell" but emerges from a dark subterranean hole through inexplicable means in a Crucified Hero Shot) were completely unintentional, but he likes it when people interpret the story that way.
Throw It In!: Tim Robbins ad-libbed Andy Dufresne turning up the volume on the speaker in defiance of Norton telling him to turn it off.
Vindicated by Cable: Back in 1994, it earned just over $28 million at the US box office; it has since enjoyed a remarkable life on cable television and home video. Ted Turner loved this movie so much, he made sure it was playing on at least one of his cable networks every weekend for about a decade (helped by the fact that he had acquired Castle Rock {and New Line Cinema, for that matter} right when the movie was about to debut), which helped the film earn back its budget and give it the mainstream recognition it never received while in theaters. You can still find it on TBS or a similar channel, even 15 years later. It's also available on Netflix.
Harvey Keitel was considered for Warden Samuel Norton.
Rob Reiner loved Frank Darabont's script so much that he offered $2.5 million for the rights to the script so he could direct it, with Tom Cruise as Andy and Harrison Ford as Red. Darabont seriously considered Reiner's offer but ultimately decided that it was his "chance to do something really great" by directing the movie himself.
Jon Favreau auditioned for the role of Fat Ass. He later told Empire Magazine that this was the worst audition he ever did and it encouraged him to try and lose weight.
Darabont initially wanted to do an adaptation of The Mist, but was warned by his agent that this would typecast him as a horror director. He promptly started looking through Stephen King's non-horror work and immediately fell in love with Shawshank. He did end up doing The Mist after getting enough of a reputation that the typecasting risk was gone.
The official screenplay ends slightly differently. Instead of the famous hug shot, Red and Andy echo their previous "man who knows how to get things" exchange, before Red helps Andy with repairing the boat. Frank Darabont mentions he found the whole scene far too "Ain't We Cute", and thus scrapped it.
Other
Unusually the voiceover narration was recorded before filming began and was then played on set to dictate the rhythm of each scene. The guide track was recorded in an Iowa recording studio by Morgan Freeman in only 40 minutes. Unfortunately, there was a minor hiss to the track which sound engineers in Los Angeles were unable to eradicate. Consequently it had to be re-recorded in a proper studio; this time it took 3 weeks.
Director Frank Darabont had to change the title from Rita Hayworth and Shawshank Redemption to just The Shawshank Redemption because several actresses sent in their resumes in for consideration thinking it was a Rita Hayworth movie. Accorting to Darabont, a supermodel's agent called him and said that it was the best script he'd ever read and his client would be perfect for the part of "Rita Hayworth"—immediately revealing just how much attention the agent had paid to the actual script.
This is one of the films on Roger Ebert's Great Films List.
from the film, mainly cut for pacing purposes, including: