I assume you are referring to Somebody to Love and Fat Bottomed Girls. I have never understood why those tracks were left off Live Killers. Yes, I know that edits and omissions had to be made to squeeze the set on to four sides of vinyl without loss of quality (to quote the liner notes), but there are things they could have done differently.
I know nothing about the mastering process (assuming that's what we're talking about here) but the original side two nudges 25 minutes, I think, so presumably they could have lengthened the other sides a bit.
I would definitely have left off Dreamers Ball. That still leaves two acoustic songs. I would also have left off Brian's band introduction and the Mustapha snippet.
They could have made the B-side of Love of My Life a non-album track. (Even better, they could have released We Will Rock You (fast) instead of Love of My Life as the single from the album.) Ditto the B-sides of Crazy Little Thing and Save Me.
I really like the live version of If You Can't Beat Them too.