While your on to the director about the distance please mention this as well -
Andy crawls through 500 yards of an 18" sewage pipe to escape the prison. The ancient sewer pipe would have been filled with methane gas, carbon dioxide and ammonia fumes and too little oxygen to support the exertions of the escapee in the time required to crawl the distance. He should have passed out and suffocated shortly after beginning his escape. Additionally, when he first breaks the pipe it shoots up like water pipe under pressure. Once inside, the water is not moving. And when he gets to the stream that this supposed sewer pipe drains into, the water is pristine.
It's pointing out stuff like this that bugs the missus, particularly if my bro is watching it as well, we have to try to resist pointing out this stuff. The auld "suspension of disbelief" shouldnt be the universal excuse for sloppyness - talking worse examples than Shawshank here.