Three Men and a Comic Book - S2-E21
Trivia: Bart is surprised to learn that the actor who played Fallout Boy hadn't died in Vietnam. This is a reference to when both AP and UPI erroneously reported that Jerry Mathers of 'Leave it to Beaver' had died in Vietnam.
Answer: He was probably irrelevant to the plot so he was not included.
Then why would Homer bring it to our attention that Bart is absent?
Ssiscool ★
It's called lampshade hanging. By drawing our attention to it the producers are letting us know they are aware it is an issue.
Yes, but even when the family is having dinner together, he's not there.
Brian Katcher