Factual error: When the guerrillas are in the Sierra Maestra, we can hear the Coqui (Eleutherodactylus coqui) singing in the night. However, this small frog is endemic to Puerto Rico and the Virgin Islands, thus not possible to be heard in Cuba.
Factual error: There is a running camera shot at the UN of national flags, the current Canadian flag is displayed but it was first introduced in 1965, the movie scene is suppose to take place in 1964.