"Vent."

No prizes will be given for guessing what my vent "set" was made out of...But, generally speaking, the Fantastic Four's security system is as good as it needs to be for the story. One of the first, regular (non-reprint) FF books I ever read featured the Trapster getting into the Baxter Building while dressed as Spider-Man: FF #218, although that could have been human error. I also recall around either Englehart's run or Simonson's, Thor and Cap show up at Four Freedoms Plaza, and the security system yells at them until they get off the roof. Is the security good enough to stop the Black Cat? Not consistently, I'd say. I'd even guess that Felicia's "tests" were almost like a fun side-project for Reed, almost like playing chess by mail: he would make improvements, then see if or how she beat them, and then make changes accordingly, with both trying to think three steps ahead of the other. 

Reed probably wouldn't be onboard with letting Felicia use Doom's time machine, but we've seen before, Ben is. I didn't originally intend for him to show up, either; he just kinda did, but it's Ben and he's the coolest. Both Felicia and Ben tease Johnny more than a bit, but that's probably to keep him from getting a swelled head, since pretty consistently in the Marvel U. I think Johnny's had Beatle-like popularity. I'm thinking of that time he burned down Empire State University, which admittedly looks bad, but large portions of his fanbase would doubtless insist he did nothing wrong. Anyway, Ben is also there because while Felicia probably could access the computers for info on the TVA and such, it's more fun to get the dirt from Ben, who has got to be a font of vaguely disparaging knowledge: you name it, he's seen it, and probably been smacked around by it, before. He of course has seen both Death's Head and the TVA before, but one thing he hasn't seen: Sat holding that bottle, so I had to cut a line about "I thought that bottle looked familiar." (She had both hands free in the last strips with her and the FF!)