The pedestrian in the street were unaware of the shoot so the crowd's reaction is real.
There are two different prop bombs used in the film. A small one for the adults and a big one for the kid to make him look smaller and more vulnerable.
The dialogue of the film is based on the short film "The Gift". This film was made for Sir Ridley Scott's Parallel Line's film challenge and one of the requirements of the film was the fact that it was limited to these lines.
The chase scene in Downtown LA was shot live on location and the reactions from all of the pedestrians were real.