Audio problem: When the first assassin runs out of bullets shortly after coming through the apartment window, his gun makes a series of rapid clicks as if dry firing full-auto, but real guns, even full-auto ones, don't keep on clicking when empty. It should either make a single click, or a nearly inaudible one. (00:44:16)
Audio problem: In the farmhouse scene where Jason is pursuing the other assassin, you can distinctly hear the calls of an American Crow and a Blue Jay, two species of birds that are not found anywhere in Europe, where they're supposed to be.
Audio problem: When The Professor is driving in the BMW, you can hear the transmission engage the next gear before he is seen completing the gear change. Shortly thereafter, you hear another gear change, but The Professor's hands are nowhere near the shifter (he's reading his orders on his cellphone).
Chosen answer: They are octopii hung up to dry in the sun. A common sight at Greek islands. If you search Google, there are pictures of them. They are humorously mentioned at http://www.thevisualrecord.com/dbphotopages/photopage.php?photo_id=80