The plan was merged from a money purchase plan into a profit sharing plan in 2002; however, it has just been discovered that the name on the bank trust account was never changed to the profit sharing plan name. Could a case be made that we never merged plans? What is the worst case scenario in a situation like this?

If the name change was the only oversight, I would think that there is enough other supporting documentation to show that a plan merger did occur.

No, The chage of name is de minimus.