Likely imitated from some World War II film, despite made and reenacted by children, short features an accurate depiction of Fairburn's Gutter Fighting, a hand-to-hand and knife combat technique largely used in the World War II (in a scene where armed soldier gets ambushed and stabbed in the neck in the trenches). Developed in 1920's by William E. Fairburn, it was used by British and Commonwealth soldiers.
In order to imitate gunshots Peter Jackson famously pocked holes in the Super 8 film, a technique he later perfected to a point that it was used in his first major feature film Bad Taste (1987).