Creator Backlash: Despite being two of the more popular episodes among fans, Graham Linehan and Arthur Mathews admit in the series scriptbook to not being entirely happy with how "New Jack City" and "Night of the Nearly Dead" turned out; the former because they felt far too much of the episode was taken up with Father Stack just being a jerk, and the latter because they were running out of ideas and had to resort to several comedic devices they wouldn't normally use.
I Am Not Spock: Severely affects the entire cast. If you were an extra in this show that's all you're ever going to be. Graham Norton averts it by simply carrying his persona to the talk-show circuit. Some of the cast who are in stand-up avert it (such as Ed Byrne), although Ardal O'Hanlon may not be so lucky. (That said, there are far worse shows to be forever tied to.)
This got so bad that Pauline McLynn (Mrs Doyle) refused to appear in the documentary about the show.
In an In-Universe example, Richard Wilson plays himself in one episode, and is driven into a rage by Ted saying 'I don't believe it!' to him.
Non-Singing Voice: Played for Laughs in "A Song for Europe"; Ted's singing is done by Neil Hannon of The Divine Comedy (who wrote most of the music for the series), and is so completely different to Ted's voice it merely adds to the ridiculousness of the song.
When describing the Beast of Craggy Island, one of Dougal's lines was meant to reveal that "instead of a mouth, it's got two faces." Ardal O'Hanlon didn't think this was funny, and when filming was taking place, decided to change the line to "instead of a mouth, it's got four arses," getting an uproarious reaction from the audience which immediately convinced the producers that the altered line should be left in.
"'Ride me sideways' was another one!" was an Ad Lib by Pauline McLynn — you can see Dermot Morgan trying not to laugh.
Too Soon: The original script for the final episode, "Going to America", ended with Father Ted contemplating suicide. However, when Dermot Morgan died the day after filming was completed, that ending was quickly replaced with a montage of scenes from previous episodes.
In a more personal version of Too Soon, actor Jim Norton, who played Bishop Brennan, revealed in the documentary Small, Far Away: The World of Father Ted that, as much fun as he had filming it, he has never watched "Kicking Bishop Brennan Up the Arse" from start to finish, as it was the only Bishop Brennan episode to premiere after Dermot Morgan's death, and he believes watching it would bring back too many bittersweet memories.