I guess the biggest thing for me is that it feels weird for the TF2 people to be intersecting with "reality" like this. The 'verse itself so far seems to be different from ours (what with Australium and so forth, and all we know about the Nazi's is that they existed and the Soldier went to Europe to beat them up). Kind of ironic that I'm having trouble suspending my disbelief because of all the pains you've taken to keep things grounded in what's actually going right now. If I started reading the story with the Sniper just arriving at the base (maybe brought in at the dark of night by a CIA-type van), I probably would just handwave it as "well, it's TF2 world, who says it can't happen).