Firetruck
We see the striking red color of the Firetruck as it roars towards it's destination. The imagery of the color pops out dramatically to the audience and demands we look directly at the fire engine. This vibrant color represents the fact that the Firemen are dangerous.
Slo-mo
Truffaut shows a bag of books falling in slow motion from the balcony of a home raided by the Firemen. The slow motion effect asks us to consider the gravity of this act, and thus reveals the importance of the contents of the bag.
Child
We see a child flipping through the pages of a book while Montag and his men are on hand to burn them. Montag gives a look to the child's father who takes the book from his son's hands and throws it into the pile to be burned. The imagery reveals how a parent must be more concerned for their child's livelihood rather than their ability to learn as if they are imprisoned or dead they have no chance at all.
Consuming
Montag burns a pile of books, and the entire frame of the camera is consumed with flames. The imagery reveals how the totalitarian government is consuming the very rights and imaginations of the people they rule over.
