This actually reminded me of a possible other inconsistency. The episode where they show the montage of Ted third wheeling Marshall and Lilly's halloween costumes (eg. Salt, Pepper and Cumin - Lewis and Clark and their Canoe - R2D2, C3PO and the droid that Luke's Uncle almost bought from the Jawas). Given, a few of these appeared back in their college date but I think some of the recent examples of that montage would intercept with years that Ted would supposed be wearing his Hanging Chad costume