Factual error: The year is 1969 when they steal the first aircraft (single engine Cessna), and there is a 757 taking off in the background. The 757 first flew on 02-19-82. (00:22:05)
Factual error: There is a reference to Hampshire College in a section of the film dealing with opening the drug trade on the east coast. The date is 1968 when the event occurs. Hampshire College was not founded until 1970.
Factual error: When George and Tuna travel to Mexico early in the film (set in late 60s at this point) they go to a plantation to buy marijuana. They arrive there in a Volkswagen bus, but this model was manufactured after 1972, known to enthusiasts as a "late bay".
Factual error: When George goes to meet Pablo Escobar, Pablo and George speak in English. As far as I know, the real Pablo Escobar spoke little or no English; certainly not enough to hold a conversation.