A mysterious child arrives through the stargate to deliver a warning, claiming that Earth is at risk of attack by a race of invisible aliens known as the Reetou who seek to wipe out all potential Goa'uld hosts.
"Show and Tell" provides examples of the following tropes:
- All Your Base Are Belong to Us: The last act of the episode involves the team fighting the Reetou on the base after one of the terrorist cells manages to sneak through to Earth undetected.
- Artificial Human: "Charlie" was genetically engineered by his "mother" in order to deliver a message to Earth, with the result that most of his internal organs have congenital defects.
- Borrowed Catchphrase: At one point Charlie says, "For crying out loud", which is usually Jack's line.
- Bug War: The Reetou fit the trope thanks to their bug-like appearance.
- Continuity Nod:
- "Mother" stated that she trusted only O'Neill (as he was leader of SG-1) as they were the only ones who treated Tonani's people with respect by not wanting to just steal the trinium from their planet.
- The team verifies that Charlie doesn't have weapons hidden in him the way other children did in "Singularity" and "Family".
- Dead Guy Junior: Sort of; the child asks O'Neill to call him "Charlie" after finding out that's what his own son was called, since his "mother" didn't give him a name.
- Delicate and Sickly: Charlie is dying as a result of having major problems with most of his organs due to being artificially created. He is taken away by the Tok'ra at the end of the episode in the hopes that becoming a host will cure him.
- Friend to All Children: O'Neill quickly forms a bond with Charlie.
- Insectoid Aliens: When visible, the Reetou have a vaguely insectoid appearance, though they're the same size as most humans.
- Invisibility: The Reetou are invisible to normal humans due to them being "180 degrees out of phase with our plane of reality."
- Knight Templar: The main goal of the Reetou rebel faction is to wipe out the Goa'uld, but they've decided to go about doing so by wiping out all of their potential hosts.
- Not-So-Imaginary Friend: The SGC assume that Charlie’s “mother” is some sort of psychological coping mechanism he invented at first, and after she shoots a computer they attempt to rationalize it as some subconscious psychokinetic ability. It’s only when Jacob confirms the story that they totally believe him.
- Oh, Crap!: Jacob and the other Tok’ra’s reaction to being told there’s a Reetou in the base.
- Renegade Splinter Faction: Both Charlie and his "mother" are keen to stress that the attack on Earth is not endorsed by the central Reetou authority and is being carried out by a renegade faction, analogous to terrorists on Earth.
- See the Invisible: The Tok'ra bring devices called Transphase Eradication Rods (T.E.R.s) that were developed by the Goa'uld to render the Reetou visible.
- Sensor Character: Anyone with a Goa'uld symbiote in them can sense the presence of the Reetou as the symbiote writhes in pain and discomfort in the immediate presence of the Reetou.
- What Happened to the Mouse?:
- Despite Selmak's warning that the Reetou rebel faction would not cease their attacks on Earth, the Reetou themselves are never seen again, though the T.E.R.s would continue to crop up from time to time when dealing with other invisible enemies.
- Charlie goes with the Tok'ra at the end as they feel he could blend with a symbiote in order to save his life. Jack even promises to visit with him, but he is never mentioned again.
