Continuity mistake: After Laurel picks her bag back up after bumping into Nick, when the two share a glance and the camera is on Laurel, she has one hand against her shoulder. When the shot cuts, both her hands are away from her shoulder. (00:03:20)
Continuity mistake: Just after Brian and the airport manager walk out of the terminal, they walk into the lobby area and the manager tells him "Looks like a full flight." When the manager says this, he puts his hand on Brian's arm. But in the next shot, his hands are at his side. (00:05:35)
Continuity mistake: In the cockpit, after Brian fails to make contact with Denver, he tells Albert to look out the left side of the plane. Albert then leaves the cockpit and Bob turns his body 90° to the left so that he can see Albert walking away. When the shot cuts back to Brian, Bob is positioned directly forward. (00:21:47)
Continuity mistake: When Bethany meets up with Bob, and they wonder where everyone is, Bethany is shown putting a cigarette in her mouth. The cigarette is straight and unbent when she places it in her mouth, but in the next shot, the cigarette is suddenly bent slightly. (01:52:20)
Continuity mistake: When Toomey's father is telling Toomey to tell the board room that he lost the money and that it was a mistake, in the shot from behind Toomey, his hands are placed flat over his ears. When the shot cuts back to him, it is now the sides of his hands over his ears. (02:10:41)
Continuity mistake: After Nick has finished explaining to Dinah that he has to get the blade out, in the close-up shot of Dinah while Nick says "Fold those two table cloths", Nick has his hand on top of Dinah's head. In the next shot, his hand is away from her head. (01:46:30)
Continuity mistake: When Albert strikes Toomey with the bag for the last time, in the shot of Toomey turning around after getting struck, Albert is holding the bag with his left hand. When Toomey lands on the ground in the next shot, Albert is suddenly holding the bag with both hands. (01:49:18)
Continuity mistake: When Albert lights the second match, in the close-up of his hand, he has the match placed between his thumb and index finger. In the next shot, it's between his thumb and middle finger. (01:37:50)
Continuity mistake: Brian tells Albert to crack open a can of soda. In the shot of him holding the can, whilst he uses his right hand to crack he has two fingers from that can, pressed against the side. Then there is a close-up of the can opening and those two fingers are now curled against the side. (01:39:58)
Continuity mistake: When Dinah starts walking over the cafe counter to find Toomey, Rudy can be seen behind with his hands at his side. When it cuts to a wide shot of the cafe, he is suddenly holding onto back of a chair with his right hand. (01:41:52)
Continuity mistake: When Rudy hands the sandwich to Bob for him to taste, he is shown holding a bottle of beer in his left hand, and his right-hand level with the left one. When Bob goes to spit out the bite, Rudy's right hand is suddenly at his side. Bob then says "That's not spoiled", and Rudy's right and left hand are level again. (01:15:05)
Continuity mistake: When Bob is explaining to Rudy that the sandwich isn't spoiled, Rudy is holding a bottle in his left hand. It cuts to Albert and Bethany for a few seconds. When it cuts back, Rudy's right hand is holding the bottle and his left hand is in his pocket. (01:15:15)
Continuity mistake: When Gaffney takes the bottle of beer off Rudy, he holds it in his right hand and takes a sip. He then turns to the bin to spit it out and moves the bottle to his left hand. In the close-up shot of him spotting the beer in the bin, the bottle has moved back to his right hand. (01:15:35)
Continuity mistake: When everyone is wondering what to do, Gaffney walks up to Brian and asks him what they do now. In the shot of Gaffney walking up to him, Brian has his left hand on the left side of his face and right hand on the right side. It then cuts to a close-up of Brian where his left hand is now on the right side of his face. (01:34:25)
Continuity mistake: In the reception area, after the frozen clock is shown, Dinah and Laurel hug. Dinah is placing her left arm around Laurel's waist. But in the next shot, her left arm is lowered. (01:00:25)
Continuity mistake: Bob removes the battery cover to a clock to see if the batteries are still inside. Once he removes the cover in the close-up shot, the cover is held so that it is pressed against the edge of the clock. When the camera cuts back to Bob, the cover is away from the clock. (01:01:40)
Continuity mistake: After Toomey has the imaginary confrontation with his father and hears Brian shouting his name, he has each hand on both sides of his face. In the next shot, his left hand is over his mouth and his right hand is over his left hand. (01:08:22)
Continuity mistake: When everyone is in the airport cafe, just as Rudy goes to take a bite out of the sandwich, it seen in his right hand. When he spits it out a few seconds later, the sandwich is now in his right hand. (01:14:43)
Continuity mistake: When Rudy goes to sit down in his seat with the others just before the plane goes to land, Gaffney can be seen in his seat with his mouth closed. It then cuts to a close-up shot of him, where his mouth is suddenly open. (00:44:45)
Continuity mistake: Dinah starts pressing a button after realising her aunt has disappeared. She is pressing the button with her right hand and has the left hand at her side. But in the shot where she goes to stand up, she suddenly has her left hand placed under her right hand. (00:08:28)
Answer: In the book he slaps her across the face during a heated argument. I can only assume that is what he is talking about.