- Factual errors: The stationery of the hotel where Ken and Ray are staying has the hotel name as "De Rozenkransje - Brugge". Brugge being the Flemish name for the town of Bruges. Even a fictitious Belgian hotel would never be named like that, because the article is incorrect. 'Rozenkrans', meaning Rosary, would indeed have the article 'de'. However, 'Rozenkransje' is the diminutive and as such would always have 'Het' as the article. Even for proficient but non-native Flemish/Dutch speakers, this is a commonly made mistake.
- Errors made by characters (possibly deliberate errors by the filmmakers): When Ray tells Ken that they are in the Basilica of the Holy Blood, named after a phial of Christ's blood brought back from the Crusades, they are not. They are in the Jeruzalemkerk, a private church built in the 15th century as a mausoleum for a wealthy merchant's family. The Basilica is the most visited church in Bruges.
- Continuity: The length of the Chloe's cigarette when she and Ray are at dinner changes between cuts.
- Continuity: The night before Ken is to meet Yuri, beer bottles are clearly visible on the nightstand between Ray and Ken's beds as they sleep. In the morning when Ken slips out while Ray appears to still be sleeping, the nightstand is vacant.
- Continuity: When Ray is preparing for his date with Chloe and is checking himself in the mirror, he is trying to decide whether to leave his top button open or button it. He decides to button it, then turns to Ken for approval and the camera cuts to a different angle. You can see in his reflection in the mirror that his top button is open. When he faces the mirror again and the screen cuts back, it is buttoned again.
- Continuity: When Harry and Ken meet in the outdoor restaurant, the type of glass Harry drinks from changes from a large glass to a small glass.
- Continuity: When Ray accidentally shoots the child while shooting the priest, in the first shot of the dead boy the child's eyes are open. In the next overhead shot they are closed.
- Continuity: When Ken is drinking alone in the bar, the bartender serves him a glass of beer that is well below full. The camera angle changes and then changes back again to show Ken is about to drink from a full glass.
- Revealing mistakes: In the park, Ken's silencer is for a .22 pistol (as evidenced by the small exit hole at the end), but the pistol itself is a larger caliber, 9mm or similar. The silencer would be destroyed by the first shot.
- Revealing mistakes: The ammunition Ray finds in Chloe's apartment is in a box marked "38 Special Live Rounds" (presumably to distinguish it from the other box marked "Blank Rounds"). No actual ammunition box would bear that marking. The ammunition Ray takes from the box is .357 Magnum, not .38spl, and would not fit in Eirik's .38 pistol. Further, the box is the wrong size for its labeling; it is clearly a box for an automatic caliber such as 9mm or similar (which may be why the ammunition is loose in the box instead of in a proper tray).
>>> WARNING: Here Be Spoilers <<<
Goofs below here contain information that may give away important plot points. You may not want to read any further if you've not already seen this title.
- Factual errors: SPOILER: Ken warns Ray by jumping off the Belfry. However, the Belfry's windows have fencing in front of them to prevent people from doing that.
- Incorrectly regarded as goofs: SPOILER: When Harry shoots Ray, his gun is loaded with the "dum-dum" bullets given to him by Yuri. These are special hollow-point bullets that are specifically designed not to over-penetrate human targets. It is highly unlikely that they would have gone through Ray and hit Jimmy. While some may regard this as a goof, the writer, Martin McDonagh, had a reason for Harry's selection of ammunition: The dum-dums, having passed through Ray, then pass through another, shorter character, completely tearing off his face. And it is that character's death, misperceived by Harry, that leads to Harry's bloody end. So even though McDonagh's dum-dums are ballistically inaccurate - expanding later rather than earlier - they nonetheless serve an important function in the story's trajectory, leading to its bloody finale.
- Incorrectly regarded as goofs: SPOILER: When Ken stops Ray from shooting himself in the head while sitting on the park bench, it is evident that the gun Ray is using was the one taken from Eirik the previous night. However, while this gun was originally loaded with blanks, Ray found some live bullets in Eirik's apartment (and even if he had shot himself with the blanks, it would have still been fatal.)
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