The original 1983 novel was largely set in the United Kingdom (with a few scenes in Norway). This movie adaptation is set in the US state of Alabama, but, ironically, was mostly filmed in the United Kingdom (though some exteriors were shot in Alabama and Georgia). Octavia Spencer is originally from Alabama.
Footage of sniffing scenes from various Looney Tunes shorts were references for the animation of The Grand High Witch smelling out the main character as he hides from her.
Acme mouse traps were used, a reference to Looney Tunes, also released by Warner Bros.
Chris Rock: in the beginning, as they are showing hero's room. You see his parents in a black and white photograph. That's Chris Rock as the father.
Charles Edwards: who played Mr Jenkins, played Michael Palin in Holy Flying Circus (2011). Michael Palin also made a cameo as one of the witches in the original movie adaptation The Witches (1990).