Mu is considered a fictional continent as it is highly unlikely that the continent disappeared (it cannot sink or be destroyed in that short amount of time). Mu was believed to have been located in the Atlantic Ocean.

Mu is a hypothetical continent that disappeared before the dawn of human history.

However you are probably referring to the island of Atlantis, according to tradition, lost about 9600BC

This answer is not scientific, but usually the lost continent is Atlantis.

The Lost Continent - 1994 was released on:

USA: 1994 (Outfest Film Festival)

The cast of The Lost Continent - 1994 includes: Joel Moffett as Narrator