content: If that was from mythbusters, the rail car that imploded had to take a significant hit to DENT the steel before the vacuum implosion thing worked. Before that it did not matter that the rail car was set for decommissioning and very covered in rust and the safety features were removed. Seriously, an inch or two of steel is enough to keep a vacuum from collapsing the shell. This is the principle for our space vehicles and submarines.