From this episode on, Sister Michael is often seen walking on crutches. This is because Siobhán McSweeney broke her leg after falling off a bicycle. The injury was then incorporated to the show.
The story Uncle Colm tells about a woman claiming her son was sired by a fellow from the Spanish Armada of 1588 is based on the myth that many of the Spanish Armada sailors shipwrecked on the coast of Ireland survived and intermarried with local Irish people and now many of their descendants live in Ireland. In fact, almost all the shipwrecked sailors were captured, were killed, or escaped back to Spain and there is no evidence to link the people of Ireland to the sailors of the Armada.
The exams the gang are worried about are the GCSEs, a standard series of exams that all students in England, Wales and Northern Ireland (but not Scotland) take around age 16. In order to advance to the next stage in their education, called A levels, they must successfully pass the GCSE's. As Clare says if they fail the GCSEs they can't do A levels or go to university.
James is wearing a Derry City FC shirt throughout the episode.
In the video shop where Dennis works almost all the posters and video tape covers are for movies which do not exist. They were most likely made by the show's props department and were made because getting the rights to use posters and images from real movies is very difficult.