Gas (1944)
After barely stumbling through a gas-mask drill, Private Snafu tosses his mask in the trash the moment training ends — and has to dig it back out of a garbage truck seconds before a parachuting cloud of poison gas catches him unprotected.
Directed by Chuck Jones, Gas was made to combat a real problem: with no chemical attacks yet seen in the war, soldiers had started treating their masks and drills as pointless — a complacency this short tries to scare them out of.
Background
Gas is one of the Private Snafu series, a line of instructional cartoons made for American soldiers during the Second World War, this one directed by Chuck Jones. The short was created to address a real problem noted by military trainers: with no chemical weapons attacks yet seen in the war by that point, many soldiers had grown complacent and begun treating gas-mask drills as pointless busywork rather than a serious safety measure.
What to watch for
Watch for how the short tries to frighten that complacency out of its audience: Private Snafu barely struggles through a gas-mask drill and then immediately throws his mask away once training ends, only to have to dig it back out of a garbage truck seconds before an actual gas attack catches him unprotected. The Private Snafu series as a whole is notable for being made specifically for military audiences rather than general theatrical release, and for using sharp, sometimes crude humor to deliver serious safety messages.