I hope I am not repeating something already posted...
In this issue, dated April 1987, the Justice Machine is attending a comic book convention on Earth.
Demon, the cutest one, with a body to die for meet a guy dressed as Northstar and who is 100% physically identical. Northstar seems interested in Demon....
Later, there is an explosion and the roof start to collapse. Demon rush to aid the Northstar guy who doesn't seem to have the power of the "real" Northstar. The northstar guy seems to care a lot about Demoncondition...
What is funny with this appearance, even if the reader think first that this Northstar guy is a costume geek, is the fact that he has the same behavior and the same physical apperance than the real northstar make us think that ...well, it could realy be northstar who is attending a comic convention.
Tony Isabella, who wrote this issue, knew Bill Mantlo. This "clin d'oeil" is even more disturbing when you look closely: Demon is hurted by falling debris at the shoulder...it will never be mentionned again.... At the same time, Northstar will be hurt at the shoulder by falling debris too in alpha flight 41, and it will never be mentionned again too. And it's almost the same dialogue from one comics to another I think (the mother of Persuasion tell northstar almost the same line about his shoulder).
Alpha flight 41 wasn't published yet when Justice Machine 4 hitted the stands but they had closed shipping dates. So did Bill Mantlo added the shoulder hit to respond to Tony Iabella? Was it the opposite? Is this scene a "spoiler" about the hurted Northstar shoulder? Did they agree to put this in each of those comics?
And lastly, in Comic Book Reader 219 (butseen also somewhere in others mags), a preview art of the never published Derangers epic series, drawn by Butch Guice: (Laura and Goblyn named Shadow!)