When Greg is at the drug store counter he asks if they have any nicotine patches. He is told that they don't but that they do have the gum. When the guy takes the gum off the shelf, it is next to boxes of Nicorette patches.
When Gaylord's MCAT scores are discussed at breakfast, Dr. Banks says "board's a killer" implying that Gaylord took the "boards" and did poorly. The MCAT has nothing to do with the "board" exam. The "board" exam is the USMLE or United States Medical Licensing Exam administered by the NBME or National Board of Medical Examiners and is taken in 3 parts by current and continuing medical students. The MCAT is the Medical College Aptitude Test which can be taken by anyone.
During the dinner scene, as Greg presents the cheap bottle of champagne, the mother calls him Rick. The closed captioning even reads as "That is so sweet of you, Rick." The closed captioning error has been fixed on the DVD (as subtitles) and D-Theater releases.
Greg explains to Jack that "Magic Dragon" refers to smoking marijuana. In fact it refers to smoking opiates. Though he probably knew it and decided to lie to Jack, because he felt mentioning marijuana to him would be bad enough as it is.
Headrests are clearly missing in both vehicles during the race between Greg and Jack after leaving the restaurant. When they arrive at the house and everyone exits the vehicle to go inside except Greg, a wide camera shot behind the parked vehicles clearly shows a headrest on the driver's seat in the Mercedes Benz which Greg is sitting in.
When Greg is trying to get on the plane at the end, the flight attendant makes him wait until his row is called when there is clearly no one else waiting to board. But when Greg does board the plane, it is almost full and there are still people coming on behind him.
Jack watches a tape of Greg in which Greg mentions Denny and hints at Denny's drug use. However, the tape is of Greg's first night at the house. Greg didn't meet Denny until his second day at the house.
When Jack is about to read his poem at the dinner table, his reading glasses are on his face instantly. The camera does leave his face for an instant, but paper is heard shuffling the whole time, so he wouldn't have had time to put on glasses.
When Pam sends Greg to borrow clothes from Denny's room, Denny climbs through the window wearing his gray jacket with the yellow stripe on it. He then takes it off and puts it down somewhere. Denny then hands Greg some clothes and he leaves. As the family comes down the stairs before they all leave, Pam tells Greg to get a jacket because it is cold outside. She then goes to a closet and pulls out Denny's jacket, when Denny's jacket was left in his room upstairs.
While trying to get his bag into the compartment, a man tries to push past Greg, which causes him to yell "where's the fire?" Annoyed, the passenger sits in the seat in front of him. However, when Greg is being dragged out of the plane you can clearly see the same man sitting in the seats in the terminal, as though he had been there all along.
When Greg and Pam are discussing Top Gun in Greg's room, Greg is wearing a hooded top and Pam wraps her arms around his neck. Pam's arms are on top of the hood, or under the hood, depending on the shot.
When Pam threw the pack of cigarettes on the roof in the beginning, they landed upside down with the label facing down. Later on in the film when Greg is on the roof, the cigarette pack is now right side up with the label facing upward.
When Greg goes onto the roof after Jinx, he spots his cigarettes thrown up there earlier by Pam. Viceroys. When Jinx eludes him, he sits down and smokes a cigarette, but the one he smokes and later flicks into the gutter is all white, Viceroys have a brown filter.
When Greg stumbles into Jack's office, the lava lamp in the bottom left hand corner of the screen is just warming up (the wax is set in a single column in the liquid). A couple of seconds later, it's working normally, with globs of wax floating up and down.
Near the end of the movie, Jack calls a source and learns that Greg is leaving on flight 27. As Greg attempts to board the plane, a sign above the gate indicates a different, three-digit, flight number.
When Jack is crying about his poem, Pam pats his arm then moves it away to take a sip of wine and puts both hands down on her lap. When we cut back to Jack immediately afterwards, we see Pam moving away from his arm again, even though her hands had been on her lap.
As Greg accuses Jack of still being a part of the CIA, Pam's hair is parted on the right. A few seconds later, as Greg becomes angry and leaves for the airport, Pam's hair is parted on the left as they go outside.
When Greg is on the roof, the camera reveals the cat dangling over Jack's head and the porch is 10 feet or more to the right. Greg drops the cat onto the sidewalk. In the next shot of Greg, he kicks at the gutter, it falls, and Greg drops onto the middle of the porch roof quite a bit to the right.
When Jack is on the phone speaking in Thai, he is shown wearing only a long sleeve collared shirt. Greg at this time has the cat by the collar hanging from the house. When the cat lands on the ground, Jack is shown walking into the house with the tails of a tan jacket visible.
At the breakfast scene when Greg is in his pajamas, he is talking and holding a bagel in his right hand. One second later, the camera view changes and Greg stands up with a coffee cup in his left hand.
On the way to Pam's parents' house, she opens the gift box. This gives the impression that the top and body of the box have been wrapped separately so that you can just open the lid. Later, when Dina opens the package she has to unwrap it like a normal flip-top box.
At the end of the movie when Jack is driving to Fiorello LaGuardia airport the sign above says two exit signs one is exit 7 for LaGuardia and the other is exit 8 for 111 St. For these signs to come up in this order that would mean that Jack would have to be driving from Manhattan, but in the movie he was driving from Long Island so the exit numbers should be going down.
Pam and Greg board a flight to Fiorello LaGuardia Airport to meet her parents. The clip of their flight shows a 747 landing. 747s don't land at LaGuardia, and even if they did, they wouldn't be used on such short flights. The clip was shot at John F. Kennedy International Airport.
Jack's deception revolves around trying to get visas for the honeymoon on Koh Samui. Americans don't need a visa to travel to Thailand. They are given 30 days visa-free on entering the country, certainly long enough for a honeymoon.
Greg's luggage should have a routing tag with his name and flight on it. At best it would be delayed but arrive at his location via delivery. There is no chance that someones luggage could be delivered mistakenly to him.
When Jack is entering the code to arm the alarm system, 7 beeps can be heard - which is not possible, the MA1000e has 4-digit user codes and requires no "enter" afterwards. Even if he arms with bypass, even number of keypresses would be required.
Kali Rocha plays both Atlantic American Airlines' gate attendant, then a flight attendant on board the same flight a moment later (without even changing uniform!). Although they may be employed by the same airline, ground staff and in-flight crew are different people - managed under different divisions, and under separate labor unions.
Greg would have had to check his bag before boarding and have a tag placed on it because it did not meet the height requirement at the gate so there is no way he could bring an oversized bag on the plane.
When Greg accidentally knocks the urn from the mantelpiece, it breaks, the lid falls off and ashes spill all over the floor like they have been sitting inside by themselves. In reality, ashes are contained inside sealed plastic bags which later go inside the cremation urn, which in turn are sealed shut.
The MA1000e alarm system has only 6 zones - it is strange that Jack, having been at CIA, fully aware of security concerns, is content with that small an alarm system, given the size and complexity of his house (the house would require at least a GEM-1632 panel with a maximum of 32 zones but that system has a slightly but noticeably different keypad).
At the airport, Jack uses his thumbs to take Greg's pulse. Thumbs cannot be used to take a person's pulse because your own pulse can be felt in your thumbs. Presumably both Greg and Jack would know this, but it could have been a trick to distract Greg from the signs Jack was really reading (sweat, eye contact, etc.).
Pam mentions that Top Gun was a very popular movie when she and Kevin were dating. The movie Top Gun was released in 1986. If Kevin was Pam's fiancée, for how long were Pam and Kevin dating? Top Gun has been a consistently popular movie ever since its original theatrical release, so she could have been referring to any point in time, really, including more recently. She never said it was when the movie was first released.
Debbie Byrnes calls her sister, Pam, to tell her that she has just gotten engaged and is going to be married in two weeks. Since the wedding is taking place at home, while this is short notice, it's possible it could have been arranged so quickly. Jack presumably has some experience in pulling together complex operations.
Jack is a skilled former CIA agent who is a "human lie detector." His son, Denny, takes a marijuana pipe out of his coat pocket, the coat that Greg borrowed. He shows it to Jack and says "I found it in Greg's jacket pocket." Jack knows that Greg lost his luggage - and that he wasn't wearing that coat when he got there the day before (so he couldn't have had that coat with him). So why does Jack, a skilled "lie detector" and CIA agent, believe Denny when he says that the jacket is Greg's?
When Greg jumps back in the house from the roof after setting the backyard on fire, his heel obviously breaks the window and it comes crashing down. This would have lead to an early discovery of the culprit had it been pursued.
When Jack calls his CIA contact to find out what flight Greg (Gaylord) Focker is on, he is told it leaves at 2:35,and Jack hurries off to LaGuardia Airport to intercept Greg. It is clearly night time (the Byrnes party was a dinner). But there are no flights that leave LaGuardia at 2:35 am, and it is the same night as the Byrnes party, so it couldn't have been 2:35 pm (the afternoon). Obviously, the wrong time was given to Jack Byrnes, who nonetheless was able to find Greg Focker.
In the very first scene, Gaylord is practicing his marriage proposal to a patient. As the camera pans past the heart monitor, the display reads "ECG Lead Fault", which means that one of the ECG electrodes has fallen off or (more likely) that the ECG electrodes were never hooked up to the actor in the first place.
When Jack is racing to the airport before Greg's plane takes off near the end of the movie, he goes from the right lane on the highway, move two lanes over and gets back to the right lane as if passing a slow-moving vehicle. But there was no vehicle in the right lane to slow him down.