In the movie ''Angels and Demons'' an anti matter bomb goes off with the energy of 5 kilotons above the sky of Vatikan. All the bomb does in the movie is it produces a strong airblast which blows people and objects great distances. The bomb sees to off at a maximum of 1-2 kilometers height in a helicopter.
What would be the real effects of an antimatter device ''detonating'' with 5 kiloton energy?
First thing to understand: the term "ton of TNT" is a rather arbitrary measure of the explosive power of ANY explosion, whether chemical, nuclear, or anti-matter.
Thus, when we refer to a "five kiloton" explosion, it doesn't matter what was the source of the explosion.
For better or worse, we have a vague idea of the result of a five kiloton blast about 1.5 kilometers above a city -- namely, the atom bomb over Hiroshima. The best estimate of its explosive power was 15 kilotons; President Truman announced it was a 20 kiloton blast, but that over-estimate was based on one observer's crude guess on the size of the explosion. In addition, the bomb was exploded at a height of 600 meters.
The effects of this bomb can be summarized here:
I haven't seen the movie, but it would seem a five kiloton bomb would have done a bit more damage than simply blowing people and objects off the ground.