Eternal Prison Deleted Areas
The Eternal Prison was discussed in a pre-release interview, and described as including a hallway that extended into infinity. It is possible that this hallway was the missing "ep03" area of the level. No known screenshots or video footage exist of the hallway. It seems likely that it was removed for technical or gameplay reasons.
Promotional video footage and screenshots of the broken stairway area of the level depicts it without a ceiling or a floor. The solid elements of the room float in a misty void.
Finally, a single piece of concept art illustrates additional nightmarish enemies for Kain to encounter in the Prison.