The Man with the Umbrella - S1-E3
Continuity mistake: When people start dying during the dalgona game and people start getting eliminated from the floor of the control room, you can see one of the screens on the left showing a player licking the back of his cookie. People don't start doing this until they see Gi-hun come up with it, and he hasn't had that epiphany yet. (00:39:26)
Continuity mistake: When Jung-bae is speaking with Gi-hun at the start, whilst Gi-hun is saying "Last time I was here, someone said the exact same thing," Jung-bae's hand is raised with a spoon in it. When the shot cuts to focus on Jung-bae, his hand is lowered. A few seconds after that, after Gi-hun says "That person died here," the shot cuts back to Jung-bae and his hand is suddenly raised again. (00:02:10)
Continuity mistake: When Jung-bae fails to get Gi-hun to eat the egg and rice, he decides to eat it himself. When he takes the spoon out of his mouth after eating it, he lowers his hand away from his mouth. When the shot cuts, his hand is raised to be level with his face again. (00:01:50)

Visible crew/equipment: During the shooting, a crew member holding a camera is visible in the upper right side of the screen. (00:22:39)