I found some info involving the Bataan Death March and Bataan when I visited Corregidor last Friday.

According to the historical guides on the island, the guns of Corregidor had inadvertently fired on the POWs of the Bataan Death March, causing some casualties.
This was documented, they claimed. Unfortunately, since I was only on a day tour, I lacked the time to look at the records on the island. They also mentioned that it was the British that first released this story while the Americans hushed it up.

As an aside, I bumped into a Japanese tourist who visited the island. On board the ferry, we discussed the Death March before I met the island's historical guides. According to the tourist, he was told that the Death March was a military necessity. It was a gruesome thing to do, he admitted but the Japanese had to use the prisoners as a human shield to force Corregidor to stop shelling Japanese positions and supply routes. The supply routes, he added, was partly the same route the prisoners took.

I don't know but this seems a coincidence. At first glance, it seems there might be something to the claim of friendly fire. It looks logical and plausible. Anybody else who has heard of this claim? It is a fact that some of the guns of Corregidor were still firing at Bataan when the troops in the peninsula surrendered.