When you shoot down into the controllable cannon just above the acid, aim left instead of right. The angle at which you fire is important (see video) because you’ll have to hit the far wall in order to do a wall jump.
When you get to the green barrel pictured above, do not ‘splode it. Instead stroll past it and continue on until you reach the shoes.
Use the Mandy that you bring down with the three conveyor belts and walk back to the checkpoint on your left. Just above the checkpoint is a recharge panel which will allow you to continue up and to the shoes.
In the first section involving cannons, you’ll have to work quickly to get in front of the flaming Wilford and ‘splode him again to change his direction. See the video.
After you make the large mid-air ascent with the series of barrels, you’ll come upon an acid pool with two barrels above it. ‘Splode the first but avoid the second in order to make your way to the other side of the pool.
When you reach the end of the portion with the floating platforms and electric beams, hit the switch and wait for a second green barrel to fall to the left of the first. Use that to get to the shoes.
Secret Exit to 2-7
This very Mario-esque secret exit can be found by using the barrels after the fifth checkpoint to blast up and to the left.
At the very beginning of the level, walk across the glass to your right. Be careful not to shatter the glass as you leap to the platforms below. Wait for the last platform to drop down to the shoes before using the barrels to return to where you started. Be sure not to land on the glass.
When you finally reach the saddled-up rocket with a 25 second countdown, ride it like you normally would. Once you hop over the low wall, run back and ‘splode next to it to move it up. Run under it and to the left until you reach an edge, and then slide down the wall in order to recharge. As you fall to the right, use your three splodes to get as much distance as possible.
Just after the second checkpoint you’ll encounter two floating baddies. ‘Splode off of them to get up the wall to your left. You’ll find a recharge panel about halfway up that will help you reach the shoes.
When you explode out of the Mandy onto the ledge, instead of continuing right, slide down the wall. Make sure to ‘splode at the bottom to open the door. Grab the shoes, jump to the right, and ride the zip lines to safety.
Just getting through 2-11 is a challenge in itself, but there’s even more work to do if you want to collect the shoes too. When you reach the portion with the pink paneling and the three floating green platforms, do not ‘splode the green barrel to your right. Instead, ‘splode over it and onto the car. The shoes are on the wall to the right.
Just after checkpoint #2, climb all the way up the conveyor belts.
At the portion where you free fall alongside the saddled-up rocket, make sure to stay just far enough away until you hit the shoes. Then grab the rocket and ride to safety.
Secret Exit to 2-14
At the end of the long portion with the acid, instead of continuing right, grab the ledge pictured above and wait for the acid level to drop. The exit is just below you.
There will be a portion in this level where you need to jump from your car and ‘splode off of two hovering robots. From there you will land in another car. Ride this one off the rails for a bit and stay in it until you see the glass window on the wall to your right. The shoes are right there.
At the start of the level, you need to drop down and work your way to the right along the pink paneling. When you hit the wall on the far right, slide down and continue right.
Another boss battle, so no shoes.