Continuity mistake: Throughout the movie in several scenes the living room has 2 couches even up until the Parks are getting ready to leave for their camping trip, 1 big one and one small. The very next scene when the Kims are getting drunk, the small couch has disappeared. This must be to make room for the Kims to slide and crawl out from under the table. The strange thing is when the Parks come back home, they don't notice that one of their couches is missing. It remains missing until the end.
Other mistake: When Ki-jung is making the fake diploma, the date she uses is June 16, 2018, indicating the movie takes place after then. In a later scene, when Yeon-kyo texts Ki-taek to meet in the sauna, the date on the text is June 12, despite being a later date. (00:11:20 - 00:44:40)
Continuity mistake: Just before the violent climax at the party, the pool of blood and the pieces of glass change position next to to Ki-woo, as the noose does. (01:51:55)
