The main removal reason is that you're writing outside what you should write to. Use LDX #$0B, not LDX #$0C.
Some other removal reasons are that sprites doesn't start moving again when the P-Switch runs out, the sprites still animate while the P-Switch is active, and it contains horribly inefficient code everywhere (not a removal reason on its own, but bad code should still be avoided).
Quote
LDA #$ff
STA $1594,x ; store somewhere
Why are you storing to here? You never read it back.
Quote
RETURN: ;\ The return label that gets called when the sprite is dead or locked is here.
RTS ;/ I added it here to ensure that the branch is in range.
Why not place this label in front of an existing RTS instead?
Quote
LDA $14AD ; if the runout timer is ff, skip
CMP #$00
BNE Check
RTS
1 
