If in reality hey only traveled for three seconds, how did they age three years?

So for in comic characters moving at normal speed (ex. Spades Slick, Ms.Paint, etc) the battleship took only 3 seconds to move between the walls but to those on the ship it lasted 3 years because they were moving so fast through space that they moved through time at a rate significantly slower than usual. The concept applied to this is a real thing called Time Dilation, I recommend you look into that for a more thorough explanation.