When Ricky gives Peter the box with his possessions in it, he also has two full glasses, one of which he gives to Peter. Moments later both glasses are empty when he stands up, without anyone having had the time to take a drink from them. The glasses also change position from shot to shot.
Holt tells Peter they're going to rob a "sports book", in Ireland this would be called a "bookmakers" or a "bookies".
The armoured car personnel and security guards in the "Heist" scene in Ireland are shown wearing police-style badges, carrying guns and firing the weapons during the heist. Security personnel in Ireland do not wear police-style uniforms or badges (it's prohibited by law). They are also not permitted to carry guns as part of their job. Firing a weapon in a public place (especially at another person) would have extremely serious consequences and shooting someone (even in self-defense) will usually result in some form of conviction for the shooter. Even the Irish police force are mostly unarmed and the use of guns by them is strictly controlled.
The security guards would not be armed in Ireland as its illegal for people to carry a firearm.
At 8:58 when Matt is taking his pistol from the dresser drawer, the cameraman can be seen in the mirror in the background.
When Peter approaches the security guards during the robbery, he demands his "200 Dollars" back. The currency in Ireland is the Euro, not the Dollar.
Holt - and Irishman - refers to a sports team as the "sell-tics" instead of "kell-tics". This is the common American mispronunciation of the word "celtic". No one outside of the U.S. would pronounce it that way.