Worst epic science fail you have seen in sci-fi?

[Rynn]

It's all about perception. My rationalization was that even though it probably would have no significant impact on their GDP, the numbers were large enough individually to cause emotional reactions in a society which hadn't had any experience with them.

Maybe but it really should have experience with that. It should be quite common for the Commonwealth government and media to talk of budgetary expenditures in terms of trillions (in double and triple digits too). The headcannon I try and maintain is that the value of their currency isn't comparable...but it's hard when they then show it being used.

On the other hand, have you ever looked at the costs of current military systems?  I suspect that Hamilton didn't, or maybe he only looked at what the UK has been spending. It seems to me that the costs mentioned in his books are, well, much too small.

They definitely are. Even assuming the technological, administrative and financial efficiency of the Commonwealth they go from no FTL starships to building dozens of them a week with new shipyards opened weekly. It would be like if the US navy (all 400+ ships of it) didn't exist and the government tried to create it as quickly as possible. A significant percentage of the government budget would have to go into it (much more than the 16% its at now). The Commonwealth should be talking in terms of hundreds of trillions.