For us to get Edward's past battle of dialogue moment, something had to go wrong with the experiment so Edward would feel the need to talk Tedd down from continuing.
Tedd's eyes looking like Lord Tedd's helped, but I didn't feel that was enough on its own.
I came up with several more serious things Tedd could have seen, but I felt they would have stolen Edward's thunder, and establish things I didn't have plans for beyond getting Tedd to say "GAH!"
It would've been a bit like shoving a boulder down a mountain just so someone close to the top would dodge it, having no idea what the boulder would run into after that, and asking everyone to immediately stop focusing on the boulder.
Fortunately, Elliot saved the day! Sort of.