Is it too early to start talking about a Bumblebee sequel? Never! With an unprecedented overwhelmingly positive reception from critics so far, the Transformers spin-off is already getting fans buzzing about where the movies could go next. And unsurprisingly, most of the people involved have thoughts.As Nerdist's Danielle Radford discovered, director Travis Knight tried to get most of his favorite childhood action figures included in at least brief cameos, but there was one he deliberately left out, and would love to spotlight next time. Which one is it? Here's a clue: he has been seen in at least one previous movie.