So, having no life this afternoon, I looked up "Rotten Tomatoes" all time worst movies. Their opening weekends, were as follows...
"Return to the Blue Lagoon". 1.277 mill. Beats Al.
"Staying Alive". 12 mill. Beats Al. On a related note, I remember the MAD parody of this flick and they called it "Staying Awake". :-)
"Wagons East" 1.8 Million
"Mac and Me" 2.06 Million
"Baby Geniuses 2" 3 Million.
These numbers were all unadjusted for inflation, as well.