Spot the Diff

Spot the Diff was the name given to a special two-hour Phineas and Ferb mini-marathon, aired on the Disney Channel on August 8, 2008 at 8 PM EST. The marathon was based around a scenario in which Dr. Heinz Doofenshmirtz had made an invention he called the Change-Inator-Inator, with which he could make various changes, particularly visual ones, to certain episodes of the show. As a challenge, the viewer would watch the four selected episodes and their modified counterparts while keeping track of which changes were made as part a tie-in on the official website.

Website tie-in
At the time the marathon aired, viewers could access a page on the Disney Channel official website with the URL http://www.disneychannel.com/SpotTheDiff (now a redirect to the show's website). There, before the marathon aired, they could print out an eight-page printable score card listing all the changes made in the four episodes, along with some listed changes not actually made in the episodes, each one with the answers "Yes" and "No" for the person to circle.

Right after the marathon, the player could go back to the website and take a "True or False"-type quiz on each of the episodes, with the correct answers applying "Yes" to any change that was actually made and "No" to the ones that weren't. If the person could answer eight questions correctly, they would have access to free, exclusive downloadables. Succeeding in answering all of the quizzes would allow the viewer to watch the then-unaired episodes "Put that Putter Away" and "Does This Duckbill Make Me Look Fat?" (which aired on TV just two days after the marathon).