If you watch the DVD after selecting the commentary soundtrack by Che's biographer, Jon Lee Anderson, it is very accurate. If you watch it listening to the original sound, you will miss some jumps in the timeline that the movie, as any movie is allowed to do, engages in.

For example, after the Granma lands in Cuba, the film skips to a scene of Che suffering from asthma. The director decided to not include the first time Che shot and killed another human being, a fellow soldier, for insubordination. But the film does show Che later doing such things.