Continuity mistake: When Greg places the luggage on counter in his apt to measure it, the front pocket double zippers are closed at the bottom of the left side. When Pam comes home and he describes the birth, both zippers are at the top center of the pocket. (00:02:20)
Continuity mistake: At his apartment, when Greg walks over to the laptop things on the desk change position, such as the bowl, which goes from being two feet to the right of the laptop, to directly behind it in the close-up, then back again. (00:02:30)
Continuity mistake: Whilst speaking to Pam at their apt, Greg lifts the luggage off the counter. In the first shot, the front zippered pocket faces him, but in the next shot it faces the opposite way - away from him. (00:03:20)
Continuity mistake: When the airline agent bumps Pam and Greg to first class, she holds out the tickets, with white at the top. In the next shot facing Greg, as he takes the tickets, the yellow is at the top. (00:05:00)
Continuity mistake: In the scene where Pam and Jack do the shortstack rhyme, Greg suddenly joins in and says "Ba ba ba ba ba ba ba." At that moment, Jack is looking at Greg. Then in a split second, when the shot changes to the other side of Jack, Greg, and Pam, Jack is looking at Greg's hand, then looks back up at Greg. (00:07:10)
Continuity mistake: When demonstrating the baby's "sign language", Jack puts a series of cards on the table. You see him start to put the "poop" card down in one shot and even hear it hitting the table and being moved slightly in the next shot. But after those shots, you see him put it down again. (00:09:05)
Continuity mistake: When Pam and Greg step into the motor coach nothing is on the counter between the sink and stove. However, in the shot facing Dina there are groceries right beside the sink, at the edge of the counter, including a box of Orville Redenbocker's microwave popcorn. (00:12:20)
Continuity mistake: When Jack and Greg are in the motor home near the beginning of the movie, Jack is talking on the intercom mic to his family in the back, then puts it down when he is finished. But, in the following shot that shows Greg talking, you can see Jack's reflection on the window, showing him still talking into the mic. (00:13:30)
Continuity mistake: When Jack and Greg honk the horn at the bus with all the girls, not including the driver, there are four girls looking out the windows at the front half of the bus. These girls have a purple bra, a pink bra with long shirt sleeves, an orange/ pink bra, and then a dark green bra. After two girls flash, the girl in the pink bra (#2) with long shirt sleeves, and the girl in the dark green bra (#4) are suddenly at the back half of the bus. Look at the lettering on the bus "Manassas University." In the 2nd shot, they are now after the "Y" in "University." (00:14:15)
Continuity mistake: In the motor coach, when Greg takes the milk from the fridge, the window shade behind Little Jack keeps moving up and down between shots. (00:14:40)
Continuity mistake: When Greg accidentally drinks milk from little Jack's nutrition supply, he spits out the milk and it dribbles down his chin when Jack tells him it's from Debbie's left breast. Greg wipes some of it off, then In the next shot, he turns around and all the milk is gone - the shot changes so quickly there wasn't enough time for Greg to wipe off the milk. (00:15:25)
Continuity mistake: In the scene where the two sets of parents meet for the first time on the island, Bernie hugs Greg leaving his sweat mark on Greg's shirt which also looks wrinkled. This changes to there being no wetness at all, some wetness and then very wet again in between shots of him. When he enters the house, his t-shirt is totally smooth and dry. (00:21:25 - 00:23:20)
Continuity mistake: When they all first arrive at Roz and Bernie's, Jack brings LJ over in the stroller. As Bernie babbles, "Bazooka, bazooka," and LJ starts crying, the stroller's orange flap (between LJ's legs) is attached to the front harness around the boy's waist. In the previous couple of close-ups of Little Jack, the orange flap hangs down between his legs. (00:23:25)
Continuity mistake: When Greg does damage control in Roz's office by hiding things, the height of the table is about Greg's waist level - also note the wood paneling trim. In the previous shot, as Greg surveys the room, the table is a foot lower, which is also seen in other shots including when Greg enters the room, after the football game, to check on Jack and the table height is level with Greg's thighs. The entire table was deliberately raised in the close-up. (00:27:00)
Continuity mistake: When Greg goes into his mom's office to quickly put away all the sex toys and objects before the Byrnes come in, on the dresser, to the left of the door, is a statue and a shell. In the next shot, after Greg has shoved the statue behind the desk, the shell has now moved from the left to the right. There is no time for this as it is shot as a "continuous" sequence. (00:27:13 - 00:27:19)
Continuity mistake: When Bernie shows off the "wall of Gaylord" the sports lamp (with soccer ball, baseball and glove) sits on the left of the dresser, with framed photos beside it. However, when everyone heads to the lagoon, there is a close-up of a framed jockstrap, which now hangs prominently beside the lamp. (The jockstrap normally hangs behind the lamp, which blocks it from view.) (00:27:30 - 00:30:40)
Continuity mistake: As they are all outside drinking Tom Collins', the 2 cherries in Greg's drink are at the bottom, then when he leans in to answer Jack's question about his 'sister', the cherries are now at the top of his glass. The cherries actually switch back and forth in several shots. (00:32:15 - 00:32:30)
Continuity mistake: Jack's Tom Collins has different amounts of liquid when they are sitting by the lagoon. (00:32:20)
Continuity mistake: After the Byrnes meet the Fockers and retreat back to their motor home, Dina, standing in front of Little Jack says "they seem like very nice people." Little Jack has his laptop all the way down by his feet. Jack then runs over when he thinks LJ has spoken his first word and you now see the computer up by his chest and some sort of small equipment appears on the seat next to LJ. It looks like maybe a cellphone or seat belt buckle. (00:34:07 - 00:34:17)
Continuity mistake: After Jinxy flushes Moses, in some shots the toilet seat is up beside the lid, but in the rest of the consecutive shots the seat is down. (00:36:50)
Answer: Truth serum doesn't automatically make you speak the absolute truth - all it can do is make you say what you believe to be the truth. If Gaylord believed himself to be Jorge's father, then he would say that under the truth serum, even if it ultimately turned out not to be the case.
Tailkinker ★
Gaylord (Greg) was also drunk when he went on his monologue of spilling "secrets" about others in the room.