The use of a credit card to place a long-distance landline fire support is based on an actual event in the Operation Urgent Fury Grenada action. A U.S. Navy S.E.A.L. rescuing the Governor General placed a calling card call to S.O.C.O.M., which brought an AC-130 gunship to bear on an A.P.C. that was firing on them.
The sequence involving the bulldozer was based on a real event. The officer who actually did what Clint Eastwood portrays was John Abizaid, at the time a Captain and a Ranger Company Commander. Abizaid recently retired as the U.S. Central Command (CENTCOM) commander, in charge of all U.S. forces in Iraq, Afghanistan, and the rest of the Middle East.
The title was derived from the Korean War's Battle of Heartbreak Ridge, also known as the Battle of Wendengli. It was fought between September 13 and October 15, 1951.
Though he has acted in earlier war movies and directed others later in his career, this is the only war movie of Clint Eastwood's where he both acted and directed.
To get into character and understand the mind of a highly decorated Marine, Clint Eastwood shadowed Marine and Navy Cross Recipient James L. Johnson (J.J. Johnson, nickname). After many deployments to Vietnam, J.J. was told he could not deploy again after requesting an additional deployment. This tough nosed man was perfect for Clint to shadow for some time. Eastwood even does a name drop for James L. Johnson during the Ball scene while wearing his dress uniform. "What would J.J. Johnson do?"