Look - it's hard enough calling a game by yourself. Pretty much, we've all done it. Of course you're going to miss a few things. If it was expected that you wouldn't miss anything, then all games would be done with one official.
As to the first call, the principle is the same whether you are out there with none, one or two other officials - if it might have been a foul, it wasn't - if it might have been traveling, it wasn't - if it might have been a carry, it wasn't - etc. You absolutely must see the foul or violation and there must be no doubt in your mind that it happened.
If the coach is the least bit reasonable (and maybe there's your answer), and you explain that in one-man mechanics you can't even come close to seeing everything but you're doing the best you can, then he should accept that.
If he doesn't - puke on his shoes.
