There's a warp pipe that'll instantly bring you to World 5 from the World 1-Tower. When in the hidden room with the second Star Coin, notice a small gap in the upper-right corner of the room that's never closed by the shifting blocks. You can jump into the gap to reach a hidden area with a 1-Up (smash the invisible blocks as soon as you enter the room). Shell Mario can go one further, breaking the blocks along the floor to reach the warp cannon.