Why was the iceberg strike 'flipped' in the underwater shot?

As is known, and shown in this film, the Titanic hit the berg on its starboard (right) side. But the underwater shot of the ship being ripped open by the berg shows it hitting it on its port (left) side.

This has been noted and commented upon ever since the film came out 56 years ago, but as far as I know never explained. It has always frustrated viewers as one of the most blatant and baffling contradictions within any film. (If they had shown the ship striking the berg on its port above water, that would have been factually inaccurate but would at least have matched the ensuing scenes.)

Subsequent to this shot, all the interior and exterior shots of the ship clearly show a list to port, which was of course historically incorrect. The very first interior shot, of crewmen running out of a hold as the hull is torn open, comports with a portside strike but that shot too looks "flipped", as if it had been filmed correctly (a starboard hit), but then reversed when it was printed to conform with this inexplicable portside gash. Take a look at it next time -- it clearly looks like a mirror image. And as the model sinks it's shown listing to port; close-ups of the passengers on the decks and crew on the bridge also plainly depict a decided tilt to port.

My question is -- how did this happen? How did one mistake someplace in the production balloon into this massively unfathomable series of absurdly depicted errors? No answer I can come up with makes satisfactory sense. Somebody screwed up badly at some point, but the decision was obviously made, not to fix the initial mistake, but to change the entire depiction of the sinking into something not only inaccurate but idiotic, to go along as though the ship's port side was damaged, even though the surface scenes of the ship hitting the berg totally contradict everything that comes after. This is such a massive mistake and utterly asinine method of dealing with the situation that it's astounding the brains behind the movie didn't take steps to properly correct it. Nothing about this makes any sense.

So -- anybody have any information as to how and why this ludicrous situation came about?