Jules Verne's classic novel Twenty Thousand Leagues Under the Seas describes a portrait of Daniel O'Connell as a freedom fighter admired by Captain Nemo. This detail was omitted in translations by Englishmen, likely for political motives.
Although the film takes place in Ireland and focuses on the life of a variety of Irish people, the actors do not use Irish accents. This is because the director felt that attempting to do accents with varying skill levels might detract attention away from the more important plot of the film. Therefore the only character with an Irish accent is grandmother Cathleen.
The Daniel O'Connell Memorial church in Caherciveen, Ireland, is one of only a few Catholic churches dedicated to a layman.
On the two largest filming days, the makeup head and assistant had to call in two additional makeup artists to help with the 100+ background actors that needed hair and makeup supervision. Magically, the team was able to complete all feature actors and background actors in order to start on time using a very streamlined scheduling process.
If you look closely in the first scene where Gavin is introduced, you can see black spots on his hand to mimic ink. This is because Gavin works with a printing press, and the makeup crew wanted to make that a visible part of his character. This was achieved by dabbing black liquid airbrush makeup onto his fingers with a sponge and spraying it with setting spray so that it would not get on his costume, but would be easy to wash off after the scene was finished.