This story of US Marines going back to Vietnam is far fetched and the flashbacks may be a pastiche of events involving a number of different units. However, they catch the spirit of interaction of Marines, their noncoms and officers. Ramsey is a very believable captain, but in reality, he would have been at least a company commander and would not have been so directly involved in unit leadership. Otherwise, his and his marines' interactions were consistent with my experience.
So take the plot with a grain of salt, but watch closely the way the marines and their Navy Hospital Corpsman and Chaplain go about their business. It will give you a good understanding of how marines think and act in a combat environment.