Apparently, somebody isn't following the money that far. I can't comment on Mary Bono, and can't imagine what there is in Rangel's district that the Federal Gov't would be spending contract money on directly (it's possible that there are some subcontractors in Harlem working for Northrop Grumman on Long Island), but there's a pretty significant amount of DoD funded work going on in Rohrbacher's district. A large chunk of Boeing's Space and Defense division is located in Huntington Beach and Seal Beach, both of which are in that district, and there's lots of other aerospace in the South Bay (L.A. South Bay, that is, not the other one), a good chunk of which is also gerrymandered into Rohrbacher's district in order to pack as many of the wealthy (aka statistically GOP) coastal voters in L.A. county into a suburban Orange County district, and there's more work being done in the area by people who commute from his district.

Maybe that money gets counted in a different district due to corporate HQ locations. One way or another, the CD breakdown of the spending is really complicated by the fact that the big gov't contractors tend to spread their sites (and the jobs created by the contracts) across multiple districts in order to ensure broad and bipartisan support for most of what they're doing (as well as to get better championing of their future bids).