坏血病

坏 = 不 + 土 : In the airplane's bathroom, there is a clear sign that it is forbidden to enter the room with dirty feet. Helga Horse is quite spoiled though, so she enters right after she went to the muddy stables and spreads dirt all around.

血 = 丶 + 皿 : Mnemonic symbol: blood transfusion.

Xu Xian hurt himself and needs to get a blood transfusion in the elevator's bathroom. He found a petal leaf as donor, which is bleeding droplets into a bowl; Xu Xian gets the blood from the bowl as infusion using some tubes.

病 = 丙 + 疒 : In engine's bathroom Brunhilde is proudly inspecting her bronze medal. She got it in a contest about having the craziest sickness by painting a colorful rash on her face.