Corrected entry: In the diner scene after Tom Cruise grabs Dustin Hoffman around the neck, Dustin Hoffman writes something in his notebook. Tom Cruise reads out loud, "pulled my neck and hurt me in 1988." If Dustin Hoffman has a complete recall of everything, why would he need to write that down?
Corrected entry: When Charlie and Raymond sit at the 21 table in Vegas for what must be hours to amass a fortune of $86 thousand, the dealer is always the same. Casinos rotate dealers between tables far too frequently for this to happen. (01:28:15)
Correction: It would not take very long at all to amass $86K. If they started with say $1000, each subsequent bet would be doubled (called "letting it ride"). With a card counting genius, this could be done in less than an hour, which is the usual duration for a blackjack dealer to stay at one table.
Corrected entry: In the scene when the doctor asks Raymond unbelievably far-out mathematical equations, Raymond answers them correctly. A few seconds later, he is asked rather simple math problems and is way off with his answers. It seems uncharacteristic that Raymond (being a high-functioning autistic, as the doctor described him, and who also stated himself that he was good with numbers) would be able to answer such technical math equations with ease but not be able to subtract 50 from 100.
Correction: Dustin Hoffman's portrayal of Savant Syndrome in this story is both authentic and credible in depicting savant skills, particularly the 'prodigious skills' of Raymond Babbitt. It is startling to comprehend an autistic savant's mathematical prowess. Raymond's ability for 'lightning mathematical calculating', even in the absence of the basic simple arithmetic skills, is a VERY accurate representation of Savant Syndrome.
Correction: In addition to the correction by Super Grover, I want to note that the "subtract 50 from 100" question involved money. The doctor asked Raymond, "If you had a dollar, and you spent 50 cents, how much money would you have left?" Raymond doesn't really understand dollars and cents, so the wording of the question may have confused him.
Corrected entry: When Charlie sees a small-town doctor to get some advice how to deal with Raymond, the doctor asks Raymond to do some mathematical stunts. He multiplies 312*123 and 4343*1234 without thinking, which is unbelievable enough even for an autistic savant, but the square root of 2130 with 8 decimals after the dot, again without a bit of thinking, is certainly too much. (00:59:50)
Correction: Raymond's abilities are exaggerated, but not as much as you think. See, for example, http://www.bol.ucla.edu/~changc/page2_5.html which describes a man who can give the square root of a 4 digit number in 4 seconds (although it doesn't say to what precision). In the film, Raymond thinks for 2 seconds or so about the square-root, so his skills are not that unbelieveable.
Corrected entry: When he's frightened at the airport, Raymond states "Qantas never crashed." Between 1927 and 1951 eight Qantas aircraft crashed and one was shot down by Japanese fighters. A total of 70 people lost their lives. In its modern incarnation Qantas has had a few near misses but no fatalities, but nonetheless Raymond is incorrect, and an idiot savant with perfect recall would not make a mistake like that.
Correction: Perfect recall doesn't mean 100% knowledge of every fact relating to every historical event. Qantas is often referred to as having a 100% safety record (though they never allow this to be used in their advertising - it makes people think they are "due") and doubtless Raymond is familiar with the claim. He isn't familiar with their operations in the forties and fifties, and there is no reason he would be. He can't recall something about which he has not been told in the first place.
Corrected entry: When Raymond argues with Charlie about having to buy his underwear at a specific Kmart store, he gives two different addresses for the same store - 200 Oak and 400 Oak.
Correction: Raymond never says, "200 Oak Street", it is always "400 Oak Street."
Corrected entry: Not too long after Charlie and Raymond leave Cincinnati by car they come across a bad accident. Raymond gets out of the car and refuses to continue driving on an interstate. According to a sign they are on interstate 245 WEST, which a) I couldn't find on a map in the Cincinnati area and b) shouldn't exist anyway as all interstates with odd numbers go in north-south direction. (00:48:00)
Correction: In all U.S. cities "loops" (joined interstates that travel around the city are designated with a prefix "2"), often are listed as "west", "east", "north", or "south". This is to give the driver a general idea of which way the loop travels, and often change in transit. In major cities all joined interstates are listed with their direction.
Corrected entry: When Tom Cruise and Dustin Hoffman are driving to Vegas in the 40's Buick convertible there is a shot through the front windshield and you can see Tom's hands on a bare steering wheel. While he is still driving in the same scene a steering wheel cover mysteriously appears.
Correction: They drive to Vegas twice, once because it was on the way and once because they turned around to gamble. On neither drive the steering wheel is covered by anything in any shot.
Corrected entry: In the diner before Raymond counts the toothpicks, a new cigarette appears when the old one burns out, though Tom Cruise didn't light one.
Correction: After Charlie gets up to make a phone call, that is before the toothpick episode, we don't see any more cigarettes, not the one he was smoking before nor a new one.
Corrected entry: When Tom Cruise is driving his car, he turns the wheel too much when he's steering, like a five year old would. If he were actually driving, wouldn't he be swerving all over the road?
Correction: It's an old restored car. Perhaps the steering is very loose.
Correction: It's not a need, it's a compulsion.