Continuity mistake: When Del and Rodney are outside Sotheby's, it is dry. When the van is rocking, it is pouring down.
Continuity mistake: When Del is pretending to be ill, Albert and Raquel say that they called the doctor in the previous evening. However, a few shots earlier we learn that Del was out with Rodney the night before.
Chosen answer: An apparent long string of illnesses.