In the scene when Desmond is cutting out the pictures of his wife, he cuts their wedding photo diagonally, so that her body remains in the photo. In the next scene, he throws the same photo into the fire, but this time it's been cut vertically - completely out of the photo.
When the man from SPCC was speaking with Doyle, a woman behind Doyle hung the same pair of pants on the line twice.
The character played by Alan Bates refers to someone as "Ferris the ferret" and then quips that it is an insult to the rodent. Ferrets however are not rodents, and are not even that closely related to them. Ferrets are from the Mustela family, and are more closely related to weasels, minks, and pole-cats which are not in the family of Rodentia.
The movie, set in the 1950s, features Irish television. Ireland's television station RTE was established on New Years Day 1962.
When the camera pans on to the accordionist it shows the accordionist playing a Saltarelle accordion which were only produced from 1984 onwards.
When Doyle and his legal team walk through Christchurch in Dublin, a block of modern late 1990's apartments are clearly visible in the background through the trees.
Though set in Dublin, all the establishing shots clearly show the city of Cork which bears no resemblance to Dublin.