Dylan Hanlon who plays "Fionn" is not in any of the montage slow motion walking scene. Dale O Brien who done the SFX for the movie got into the boiler suit. The crew had to teach dale how to walk like Dylan and he kept his head down for most of the close ups.
David O Gorman who played the boss had 2 names in this movie. At the start of the movie in his office he is called "John" and then towards the end of the film in the kitchen he is called "Brian". This is because the first scene they shot was in early 2016 and they decided to call him "John". A year and a half later they shot the kitchen scene and forgot they gave him a name so they gave him another name "Brian" because in the script he was just called "Boss"
The 2 men fighting the lads in the toilet are actually the enforcers in the balaclavas. Adam Behan (Leader) has the short hair wearing the black t-shirt and fighting Scott. Dave Boyle (Strong henchman) is the big guy with the beard and long hair fighting Paul. Joe Reid (D.O.P.) is also the man pissing in the toilet watching the fight.