I remember using this disassembly many years ago when writing a little NES emulator. Having a reference available for a popular game is incredibly useful.
The byte here is for the BIT instruction, but why is it just a lonely byte? Well, the BIT instruction in this case also includes the two following bytes. When the game processes that instruction, the `ldy #$04` is swallowed up as part of the BIT instruction, effectively skipping over it. IIRC this was a pretty common trick used among 6502 programmers. It allows you to jump ahead over the next (2byte) instruction with just a single byte!
Here's one of my favorite parts: https://gist.github.com/1wErt3r/4048722#file-smbdis-asm-L942
The byte here is for the BIT instruction, but why is it just a lonely byte? Well, the BIT instruction in this case also includes the two following bytes. When the game processes that instruction, the `ldy #$04` is swallowed up as part of the BIT instruction, effectively skipping over it. IIRC this was a pretty common trick used among 6502 programmers. It allows you to jump ahead over the next (2byte) instruction with just a single byte!