Movie Goof (continuity error): In the shot of Ben counting cards on the first arrival in Vegas, Ben's tray is down. If the plane is as close to arriving as the view from the window shows, the trays would have to be in the "up and locked" position.
Movie Goof (factual errors): There is no class 2.09 at MIT, though the 2.09 class seems to pay homage to 2.70 (aka 2.007) which is a renowned robotics competition.
Movie Goof (continuity error): When Ben is handed his earnings from the first night a five dollar bill is seen on the outside of the bundle. Moments later a $100 is on the outside.
Movie Goof (errors made by characters, possibly deliberate errors by the filmmakers): When Miles shows Ben the source code of the robot, Ben looks at them and immediately says this is very good. Actually, even a highly experienced programmer could not understand a source code just by looking at it for 2 seconds, especially the code of a really complex system such as this robot.
Movie Goof (errors in geography): In the montage scene showing the "extravagant" lifestyle of the group, the film cuts to scenes at the blackjack table, inside of clubs, etc. It's supposed to happen in or around the Planet Hollywood Casino/Hotel, but many of the locations shown are from Red Rock Casino game room and the club "Cherry". Red Rock is about 12.5 miles northwest of the Strip, surrounded by houses and deserts.
Movie Goof (errors in geography): There are multiple errors in Vegas hotel locations - seeming to be in one hotel when the shot from the window makes it clear they are elsewhere, particularly when visiting a suite said to be at the Hard Rock but clearly the view is from a tall Strip hotel. The Hard Rock Hotel is neither.
Movie Goof (plot holes): In two separate places in the film, the player is hollering for the dealer to draw a "monkey" (a face card or a ten) when, in fact, a monkey would have given the dealer a winning hand. The first instance is when an Asian woman introduces the main character to the slang. The more egregious of the two instances is when the main character (who, by this time in the film, has established his big player credentials) calls out for a monkey twice when either of those times would have given the dealer a winning hand.
Movie Goof (continuity error): When Mickey and Ben are walking through the park before the first trip, there is no one behind them. The camera changes and there is a woman walking her dog and another man.
Movie Goof (errors made by characters, possibly deliberate errors by the filmmakers): Jill says that she is "comped" a suite at the hard rock hotel, however as a counter/spotter she should only be making minimum bets, which wouldn't be enough to get a free suite out of a Vegas Hotel.
Movie Goof (crew or equipment visible): When Ben leaves the Hard Rock Hotel after their first night in Vegas, the shadow of the Cameraman and Camera on the dolly are visible on the hotel front and security guards in the background.
Movie Goof (continuity error): When Prof Rosa calls Cole, Terry answers the phone and places Rosa on hold. However, when Cole takes the phone from Terry, he does not take Rosa off of hold and proceeds to talk to him.
Movie Goof (continuity error): When Ben is riding his bike on the bridge, a young guy with a lady are passing in the back stage. After this, when a yellow stripped bus passed behind Ben, that young guy and lady disappeared (it seems, they jumped into water) then another lady in white jacket appears who was absent before in the back stage.
Movie Goof (continuity error): When Ben meets with Mickey and the group for the first time, he explains the basic rules of 21 and deals himself a face-up card, then the camera cuts to Ben then back to Mickey and now Mickey's card is face down.
Movie Goof (errors in geography): Later in the movie Jill tells Ben the Hard Rock has comped her a suite and asks him if he would like to see it. In the next scene they are in a suite over looking the Bellagio fountains. The Hard Rock is not on the Strip and does not have that view to the Bellagio fountains. The suite is more likely to be in the Planet Hollywood (the old Aladdin) or even Paris.
Movie Goof (continuity error): During the first meeting with Ben, the cards that Micky deals alternate from face up, face down, and missing altogether.
Movie Goof (factual errors): In the scene were we first see Ben in the casino playing for the first time, the count is +18. We then see a face card (worth 10) appear and Ben wins. Micky then asks him what the count is. He says +18, but it's really +17 because a face card has a value of -1.
Movie Goof (factual errors): In the MIT grading scale for undergraduates, GPA is out of 5.0. On numerous occasions throughout the movie, it is stated that Ben has a 4.0. On the MIT scale, this would be a "B" average.
Movie Goof (continuity error): During the chase seen at the end of the movie Kate Bosworth's character alternates between running in heels and running barefoot.
Movie Goof (revealing mistake): All the cards in the casino scenes have rounded corners opposite the index numbers, identifying them as used cards that have since been removed from use on the casino floor and altered so they can never be sneaked back into play.
Movie Goof (continuity error): During the opening scene montage, when Ben is riding his bike across the bridge, the position of his backpack changes several times.
Movie Goof (factual errors): In the beginning of the film, Ben receives a promotion in his job at the mens wear store, and a raise to $8 an hour. In Massachusetts in 2008 the minimum wage was (and still is) $8.25 for retail workers.
Movie Goof (incorrectly regarded as a mistake): "In the prize behind three doors game, the strategy of switching doors actually gives your overall odds to win of 50%, not 66%. Say the doors are A, B and C and the prize was behind B. There are four outcomes using the strategy: 1.You choose door A. Door C opens and you switch to door B, and win 2.You choose door C. Door A opens and you switch to door B, and win 3.You choose door B. Door A opens and you switch to door C, and lose 4.You choose door B. Door C opens and you switch to door A, and lose There are two scenarios that you win and two in which you lose. The probability of winning is 2/4 or 50%. Note that #4 is actually different than #3 and is disregarded by the movie, giving the 66% odds. Similar scenarios work if the prize was behind door A or C." This theory is actually incorrect. This scenario is referred to as the "Monty Hall Problem" and it's solution is a counterintuitive, making the problem a veridical paradox. Many explanations exist, but the easiest is this. If I initially chose door A for the car, I have a 1/3 chance of winning the car. The game show host, knowing the location of the car will open a door with a goat. Once a "goat door" is open, my original probability of 1/3 still exists, as I chose when 3 choices were present. Since the chance of the car being behind the opened "goat door" is zero, the remaining door has a 2/3 chance of having the car as the total probability of choices must equal 1, or 3/3. Therefore, you double your odds of getting the car by switching you choice.
Movie Goof (continuity error): The first night the group gambles in Las Vegas they are in the Hard Rock Casino, however the table at which Ben gambles says "Red Rock Casino". When he switches tables it says "Hard Rock Casino."
Movie Goof (incorrectly regarded as a mistake): This movie is inspired by events which happened around 1994, but it is not a period piece. The fictional story it tells is set in 2008. Clues that this is so include: the presence of such entities as Amber Bock, Google, Geico, the Transportation Safety Authority; a $20 bill design first used in 1998; posters for movies such as Freedom Writers and I Am Legend, the date on Ben's mom's $68,000 check, and a clear view of the Bud Light bottle's label which reads 2008.
Movie Goof (continuity error): When Ben's mom is serving birthday cake to Ben and his friends, she serves Cam twice.
Movie Goof (continuity error): During the opening credits, while Ben is riding his bike on the road, you see the same orange PT cruiser go past twice and the same silver Chrysler 300C go past three times.
Movie Goof (factual errors): SPOILER: A key clue that makes Cole Williams suspect Ben of being a card counter is that Ben did not double down on 11 when the count was "cool". Basic blackjack strategy dictates always doubling down on 11 (because the odds of making 21 are very high - even casual players know this). The only situation where it would make sense not to double down is if the count was very negative (lots of low cards in the deck). But as the "big player" in the MIT system, Ben would have left the table long before the count became negative.