You can press 'left' for 1 frame while running to the right to decrease your subpixel value by one unit. This is the result that you want when optimizing your X-subpixel position. At other times you might have been able to be inside the wall partially. Now when you jump into a wall (not doing this trick), you might be pushed out immediately without having entered the wall at all. In this game, 16 subpixels make up 1 pixel. A subpixel is a position component which is not rendered onscreen. You will need to have a proper X-subpixel position value for this to work. Since Mario accelerates faster into the direction he doesn't face to, you should use this trick while jumping backwards (Mario faces to the left).

If Mario bumps into the left edge of an obstacle (wall, pipe, coin block etc.) while jumping, the screen scrolling will momentarily stop even if Mario continues to move to the right.

If you enter a wall, the wall will automatically transport Mario towards the right edge of the screen without scrolling.

Teleport to the right edge of the screen the vine glitch (explained above).Methods of moving to the right side of the screen (Example: In 8-4 of SMB1, in the area before the water area, instead of going in the pipe after the lava pit, go a little past the previous pipe, and then turn around and go in that pipe, and it will take you to the water area instead of taking you back to the beginning of the level.) If the screen is ahead of Mario (Mario is on the left side of screen), the variable will have updated too soon, so you can access a future entry point's target from an earlier entry point.The only thing needed is that the screen hasn't scrolled too far when the pipe is entered.) Making the vine appear is not required for this glitch. If Mario is far on the right side of the screen, the entry point variable will be out of date, so a new entry point will lead to the target of the previous one (Example: In 4-2 of SMB1, if Mario is far enough on the right side of the screen, he can use the pipe to go to the warp room since the destination info of the vine is still valid.Loaded from the level data, all entry points in the current screen will Once the screen scrolls far enough for the next target label to be In the game RAM that determines where pipes or vines in the current screen lead. The reason lies in how the game is designed: There is just one global variable

Theory: The game can have only one 'entry point' (a pipe or vine) per screen.

Super mario bros 3 world 6 maze