The disc that came in the 2012 coffin box contains Back to the Black Lagoon, production photographs, feature commentary with Tom Weaver, 100 years of Universal: The Lot and trailer gallery so the features seem to be identical.
The 3D is on the same disc as the 2D version in the coffin box, so I assume the regular edition was the same. Is the steelbook 2 discs? It implies it's 2 discs on the front of the card '3D Blu-ray + Blu-ray' but it feels too light to be more than 1 disc (I own it but have never opened it).
Edited to add: it's just the same disc from the amaray and coffin box (as pictured on page 2 of this thread).