Will Smith grew so enamored of his canine co-star, Abbey, that he tried to adopt her when filming was finished, but the dog's trainer could not be persuaded to give her up.
When Dr. Robert Neville sees the mannequin he calls "Fred" outside on the street, it looks like the mannequin moves its head a little. During that scene, a mime replaced the mannequin to try and play with people's minds when they watched that scene.
When he was in pre-production on this movie, Director Francis Lawrence found himself watching The Pianist (2002) with the sound off in order to not disturb his sleeping baby, and he found the quiet effect was extremely moving. He then made stark silence, with limited ambient effects or musical cues, a major part of this movie's process.
Will Smith talked to former prisoners to get an understanding of what it's like to be totally alone. The prisoners told Smith the key to surviving solitary confinement is creating a rigid schedule.