During the Mailtime Letter segment when the kid sees the doctor, a very rare Blue's Clues poster is seen
Noggin and Nick Jr. both ran this episode several times because of the popularity.
It is possible that Steve actually did not have a real-life cold in this episode because he didn't have any other symptoms, so it was possibly allergies causing him to sneeze and have a runny nose. Besides, he could not be having allergies if eating vegetable soup alleviated his symptoms, so it is more likely he was recovering from a cold the day before.
The oranges that were right by the bowl were peeled when Steve found the 2nd clue because Blue ate them.