You can still get the minus world bug even if you go above the top of the screen. If you only fix the scroll stop AND bug, do the normal minus world bug, reach

You can still get the minus world bug even if you go above the top of the screen. If you only fix the scroll stop AND bug, do the normal minus world bug, reach the right side of the screen, jump up on top of the level (to unlock the scroll), and drop down into the warp zone room as soon as possible, then the text hasn't loaded yet but you can still enter the pipes, which results in the normal minus world behavior. The real bug is that the scroll stop unlock object, for some reason, increments the variable the video author calls WarpZoneCtrl, resulting in it containing a value of 1, while the actual warp zone routine expects 4, 5, or 6, which it subsequently ANDs with 3 (removing all but the bottom two bits, leaving 0, 1, or 2). Entering this subroutine with an incorrect value of 1 results in the value remaining 1 (since 1 AND 3 is equivalent to 5 AND 3) and thus treating the warp zone as world 5, which is corrected when the routine that prints the warp zone text appears. The real minus world bug is the incrementation of WarpZoneCtrl. Removing that, and keeping the value at 0 until the warp zone text loads, makes the pipes use the last known pipe destination - the L-pipe that leads to the normal 1-2 level end. The video author did not discuss level 4-2, but I would presume there may be a similar scroll unlock object present at the end of that level (in fact, my long history of playing SMB1 leads me to remember that I feel like I have also experienced in 4-2 that slight scroll hiccup the author mentions if you jump just right and keep the low bit of your X position set). However, since the standard end-of-level warp zone in 4-2 is meant to take you to 5-1, and there is only one pipe, the minus world bug doesn't apply as entering the routine with WarpZoneCtrl set to 1 is equivalent to entering it with WarpZoneCtrl set to 5.