The Big Cube is a 1969 American thriller film directed by Tito Davison and starring Lana Turner, Karin Mossberg, George Chakiris, Daniel O'Herlihy and Richard Egan; it was one of Lana Turner's last movies. It is notable for its aggressive portrayal of LSD use and the 1960s youth counterculture as vicious evils.
The Big Cube was the last film Lana Turner has been in.
It states clearly that it was ONE of Lana Turner's last movies so it could be neither correct nor incorrect. The system is confused what the term "one of" might mean in this context.