S4: Ep.27 - Now that Lex is a celebrity, he's mobbed everywhere he goes by people, mostly girls, wanting his autograph. It seems he has now learnt to write, or at least his own name, "Lex". Mouse & Sammy have an idea to make themselves rich.
Salene, ever the mom to younger kids, finds Mouse and Sammy in Alice & Ellie's old room. She reminds Mouse it's her bedtime.
When she's gone they inspect what just came off the printer: a signed picture of Lex. This (or multiple copies of it) is what's going to make them money. So how did they put this "collectible" together?....
Earlier in the evening Sammy (posing as a besotted fan) asked Lex for his autograph.
Minutes later Mouse asked to take his picture.
Remember they are now in Alice & Ellie's old room, the room where Ellie put together the Newssheet using the computer (an iMac) she got for Jack.

So there's Mouse scanning in Lex's autograph. All they need to do is combine it with the photograph and...voilà!

And now the goofs....
Goof #1: The Technos raided the Mall and took away Jack's / Ellie's computer in Ep. 13 when they caught Ellie trying to strangle Ebony in her bed at the Hotel. And of course they didn't return it!

There's another goof shown in this pic, detailed elsewhere.
Goof#2: compare Lex's autograph as written by him, and the supposed scan of it added to the photo. Look at the "X". They are similar, but pic-left has small loop+long "arms". Pic-right has large loop+short "arms".

Mouse puts the camera so close to Lex, that even with a mega-tera-supa-dupa-wide-angle lens, she'd most unlikely get any of the table in shot. And besides - his right arm isn't in the same place.
  picture rotated (by me) to
give a better comparison