During Frank Underwood's hallucinations, Zoe has a significantly different hairstyle than during the first two seasons. If she is a figment of Frank's imagination, he could of course imagine her with a different hairstyle but it is more likely that the image that haunts him is the image of how he saw her during season 1.
When Cathey and Claire arrive at Brandenburg there is a shot of their car led by a German police patrol car which has a Berlin plate. While it is possible that they would get a Berlin escort all the way from the airport (they most likely would have arrived at Berlin Tegel) the plate has letters after the initial B (for Berlin) and the registration seal sticker - Police cars in Berlin only show numbers after the sticker. On the plate above the registration seal there is a emissions test-sticker visible. These stickers aren't in use since 2010.