Recently I have been trying to get a sub 5 run. I have been using OpenEMU and I noticed that when doing the backwards bump method on 4-2 Mario appears to move much farther forward on the screen. He moves so much farther on the screen that I can do the wrong warp with only one backwards bump. Is this something with OpenEMU and if not what is happening that causes him to move so much further forward?

OpenEMU emulates the physics of roms 100% the same as other emulators - it just runs on Mac (although it does run at 60fps flat instead of the original framerate)

The one thing that DOES act as you described is the PAL version of the rom - backwards (and forwards) bumps move you significantly farther. Also - the music sounds faster and higher pitched.

Pick a run on the leaderboard and listen to the music - then listen to your music. Does it sound sped up relative to the "normal" (NTSC) version? You're playing on a PAL rom.

Also on the PAL rom - doing the 8-2 intro stairs is impossible without slowing down