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: During the fondue dinner, Little Jack is in his crib, which is right next to the table between Dina and Jack. Then in the next couple of shots the crib is gone, it then reappears again at various times with and without LJ. (00:38:30)
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 everyone goes to town Greg stays behind to babysit. Just before he goes to check on a crying LJ be pauses outside the door and the shot shows a close up of a pair of running shoes that are different than the ones Greg is wearing during the remaining scenes. In the shot by the door, the shoes are light grey and white with a metal plate on the side, however, in the rest of the scenes he has on navy and white running shoes. (01:01:50 - 01:03:00)
Continuity mistake: When Greg is talking on the microphone towards the end, it appears in his hand. However, the next time he pops it off the stand, it makes a loud noise that wasn't there the first time.
Continuity mistake: During the party at the Good Times Supper Club, when Jack holds out Dina's wine spritzer, in the shots facing Pam the drink has a deep golden color, but in the shots facing Jack the drink is clear. The straw, lime, etc change as well. (01:21:10)
Factual error: The license plate on the sheriff's car is not correct for a Florida sheriff. Per the state of Florida's DMV (Dept. of Motor Vehicles) website, there should be a yellow star to the left with "sheriff" printed inside. (01:37:35)
Continuity mistake: There are two sofas in the Fockers' living room, the large whose back faces the kitchen and small whose back faces the "wall of Gaylord"; their pillows have coordinating large and small floral patterns on both sides. When Greg brings crying LJ into the living room, the three pillows on the small sofa have the small pattern facing out, but after Greg answers the phone call from Roz, Jinxy releases LJ, and in the close-ups of LJ the large pattern faces out. Then, when Greg rushes in with his rum surprise, in the first pan of the empty room the small pattern faces out, yet when LJ sits with his glued hands the large pattern faces out. (01:06:00)
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: 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)
Revealing mistake: When they show the bus with the college girls going by, as they pan over the driver, you can tell there is no door on the passenger side. You can see all the way to the ground and road of, what appears was a blue screen background added. This is made even more obvious by the fact the girl driver is not wearing a seat belt, is supposedly flying down the highway, and if this really was a huge hole in the side of the bus, it would be extremely dangerous as she could fall out. There also seems to be some sort of white mattress pad right next to the driver. (00:14:05)
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: As they are playing football, when Bernie tackles Jack, you see Jack flying and landing in front of the gate. The left flag/marker is also in front of two trees. After they show everyone running over to Jack on the ground, he is lying way far left of his original position. Now the fence is behind him, the gate is gone, and the left flag is no longer in front of the trees. (00:54:48 - 00:54:56)
Continuity mistake: In the first movie, Pam says she received a fax (MCAT scores) from Greg's parents in Detroit. We see in this movie that Greg's parents have lived in Florida for many years.
Revealing mistake: When Jack tells Greg to throw the brick at the RV, when he picks it up you can see it's some kind of spongy material.
Continuity mistake: When Jack is leaving the island with LJ, there is a shot with everybody screaming for him to come back and you can see the RV has driven about six feet from Bernie's slippers. Then there's two more shots which takes up about 5-6 seconds with everyone continuing to yell. But afterwards, the RV is only about 2 feet from where it was. (01:35:40)
Visible crew/equipment: When they are playing football, they show a close up of Jack's face after Dina makes a touchdown and she and Bernie celebrate. In the close up of Jack's face and sunglasses, in his left eye, you can see the reflection of a square camera light. This shows up again right as Jack is about to be tackled by Bernie, this time in his right eye. It follows Jack as he rises in the air to catch the ball. (00:52:15 - 00:54:45)
Continuity mistake: When LJ speaks his first word, everyone runs into Roz's office where his crib is. They show it right inside of the door. Jack then blows up at Greg when he learns it is a curse word and calls an immediate family conference. Roz, Bernie and Greg leave the room. When they show the family conference, Little Jack and the crib are now gone. (01:10:55 - 01:12:05)
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.