If SM2=1 and the address won't match, you jump to GO_ON and forget to POP ACC.

Generally, it is a bad idea to have multiple exit points from the ISR. It is better to have a self-cointained ISR ebraced by the entry/exit code:

ISR:
   push what needed
   -----
   make what you want, including
   branches and bypasses
   for example:
   if in byte receive mode, jump to BYTE
   if address not match, jump to EXIT
   flip mode
   jump to EXIT
BYTE:
   do what you want with byte
EXIT:
   -----
   pop (in reverse order) what was pushed
   reti

JW

PS. That having a single register (B) for receiving multiple bytes is an another bad idea, I leave for others to comment on...