It's easy if you can beat the level W2-2. Then beat W2-3 and you unlock the cannon level. If you want to go on, Use the pipe. If you don't want to skip levels, play the W2-3 level again. Then you unlock the next level (In the same world). The cannon goes to W5 (World 5).
in world 1 at the tower there is a red flag that you need to get to unlock the cannon.
you can unlock a level with a pipe and cannon around it (i got it on a red flag on world 2 number 4 ) and finish that on a cheat flag( the yellow pipe above the other 1). this will unlock the cannon.
you have to finish the level
You go to the midway castle
it is not stars it is a world
There is no cannon on world 1
Go into the first castle and when you get to the partwith the 4 rows of falling blocks run and jump at the black part of the left wall.
Complete level 6 sfeb5h6bgtegbu
look up super Mario bros Cannon world 1 and level 1
The French tank of World War One had a 75 millimeter cannon on its turret.
level 3
I think you mean how to unlock it. -Either complete World 5 by defeating the boss with MINI MARIO. -Or unlocking the cannon on World 4.