There is a point where 'oblivious' becomes just plain 'stupid' and Pip crossed over it and then some. The only hope they've got at this point is that Pip's little 'quip' was such a non-sequeteur that the aliens might not even work out that their cover has been blown.
I think we all agree that isn't unlikely.
On the bright side, if these guys are anything like other infiltrating aliens, they'll want to take the Luckless Trio to their headquarters so they can be analysed in depth and monologued at by their leader. As a consequence, they'll have plenty of opportunities to learn the plan, the weaknesses and, if necessary, have the option of selling Cameron down the river to save their own hides.
ART: "Pip, in the unlikely event we survive this, I'm going to cut your head off and mount it on a pole in the town square as a warning to the next ten generation about the importance of impulse control."