Thomas gets jerrycans for his trip. Jerrycans were designed in 1930. The word "jerrycan" originated during WWII when the British found German fuel containers in the North-African desert. So there were no jerrycans in 1921.
At 26:20 Polly is sitting in the bathtub and lights her cigarette with a white Bic lighter. Bic lighters were invented in 1973.