When Mike Vernon returns to the supposedly overheating hospital, his breath is clearly visible as he emerges from the sewer.
Immediately after Mr. Blackburn falls to the floor of his garage, during the handheld camera shot that provides a closeup, we see the cameraman's shadow on the garage wall.
When Mr. Carter is thrown through the windshield of his car, nobody bothers to check if he might still be alive.
When Dr.'s Vernon and Harland, Mr. Carter, and Major Muncaster first notice the hospital's temperature rising, the boom shadow becomes visible across Mr. Carter's back.