Trivia: When the alien's hand comes out of the coal grate for Morgan, if you look closely you will see that the hand was already through the grate and the alien was using its colour changing abilities to hide. So if you look very closely you will that that the hand comes UP from the grate and not through it, and if you look VERY carefully you can see the outline of the hand even before Morgen says "What?"
Trivia: M. Night Shyamalan originally wrote the characters of Graham Hess and Merrill Hess in their late sixties. The two young children were not Graham's children but his grandchildren. The role of Graham was offered and turned down by both Paul Newman and Clint Eastwood. When Mel Gibson expressed interested in the script, Shyamalan rewrote the Graham and Merrill characters to be younger and the two children were Graham's instead of his grandchildren.