
Factual error: The 20 banknote shown is multicoloured, but the real one is plain blue. (00:40:40)

Factual error: When talking about the planned robbery of Fenway, the florist mentions a four-game series with New York. However, later the crew is in a bar and a clip of the baseball game is being shown on the television. The game being shown is against Toronto. Since this scene is supposed to be just prior to the heist, one would expect the visiting team to be the Yankees, not the Blue Jays.
Suggested correction: There's nothing to indicate the clip in the bar is from a current game. Sports networks often show classic games in repeats.
Give me a break, they screwed that up.
Suggested correction: A robbery of that size and risk would require several days of planning and preparation. Doug and Jem probably went to the park during the series against Toronto to scope the place out, and the planning and preparation continued until the end of the series with the Yankees when the robbery occurred.
Suggested correction: There is no indication on what day it is. It's possible that it's Wednesday before 4 days. Or it's Thursday making the series get played on Friday, Saturday, Sunday, Monday.

Factual error: In the very first shot of the movie, a clock is shown ticking. The time on the clock reads 05:59:56. It is obviously AM because a few seconds later at 06:00:00, Frank wakes up as if it was morning. As Frank sits up, clear daylight is visible outside of the window. This scene is supposed to be set during winter. We know this because there are many Christmas decorations. Since this is meant to be winter, it should still be dark at that time of day. (00:00:40)
Suggested correction: At the beginning of the movie it's September or early October if latest in the year. At Cleveland's latitude there's enough sunlight at 6am to experience such lighting through a window facing south.
First, what in the film places the opening scene in Sept or Oct? There's too much snow on the ground for it to be either of those months (it doesn't snow in September and rarely in October, but only late October). Second, even if it was set in October, the sun doesn't rise until around 7:30AM or 8:00AM.
I disagree. I think what Bishop73 wrote above is correct. The opening scene at 6:00 AM showed daylight, which would be too early for October, November, and December in Ohio. The movie apparently begins in December based on the amount of Christmas decorations in the neighborhood. Sunrise might be between 7:30 - 8:00 AM and twilight is about 30 minutes prior to sunrise. It simply would not be that light out at 6:00 AM.

Factual error: Bobby extracts two teeth to get the combination to the next room. When he looks at the teeth, the numbers are on the tooth root. To do this would be impossible without removing the teeth first. (01:02:05)

Factual error: Clooney refers to the rifle as an "M14". The Rüger Mini-14 is a different rifle than the M14 (used e.g. by the Marine Corps prior to the M16).

Factual error: In the scene when they are leaving the Pittsburgh Zoo, the sign indicates to turn right for Interstate 79. However Intestate 79 is about 15 miles to the west of the zoo. Also, it is suggested that Interstate 79 is the turnpike (a tolled road), when actually Interstate 76 is the turnpike and Interstate 79 is not tolled.

Factual error: In a very early scene, just as the young girl is pulling a cellphone out of her vagina, if you look closely you can see that the "cellphone" she is holding is actually an iPod Nano 5th generation, which does not make phone calls. (00:04:20)

Factual error: The attack on the OPEC meeting in Vienna takes place on December 21. Yet, when Carlos' team exits the tram, the trees are full with green summer leaves and the sun shines as it would on a high summer day.

Factual error: In the chase scene where Lou is running after the derelict, they pass a number of vehicles parked and driving on the streets. All of them are correct period vehicles for the late 1950s, except for a white semi truck which is from at least the mid 1990s. The grille and headlights on the truck are the giveaway. (01:23:20)

Factual error: The movie is set in 1979-1980. You can see vehicles all throughout the movie that were manufactured after 1980.

Factual error: In golf scene, Kevin Spacey is supposed to be playing golf in St. Andrews. The intensity of sun and the surrounding fauna suggests they are actually playing on a course in the mid latitudes of the US. (00:11:30)

Factual error: When the Senator is looking at the rent ledger, there are entries for each property as well as the date that money was collected. One of the dates is 2/29/74, yet 1974 was not a leap year. The only leap years in that decade were 1972 and 1976. (00:56:30)