I'm not entirely sure what House is holding here? Syringe needle tips?
Those are IV needle canulas, more precisely the plastic-tipped ones. The different colors marks different needle sizes (which correlates inversely with the size of the aperture, the larger the number the smaller needle it is and vice versa). There's a lot of possible scenarios here, including the nurse (Callie) installed a canule with too small of an aperture in case of severely dehydrated patient, pierced too deep and bent the plastic part, or simply didn't manage to get the vein correctly.
