Revealing mistake: When the team lands on the Planet and first step out of the Puddle Jumper, you can see multiple footprints going in and out of the puddle jumper from previous takes.
Revealing mistake: Steve (Wraith)'s belly appears not to match the rest of the Wraith character's skin tone. Clearly, it is a human body rather than an alien. (00:31:36)
Answer: Because even all 4 Naquadah generators (one was destroyed) together is only enough to dial Earth for approximately 1.2 seconds (As seen in the episode "Letter from Pegasus"). Further, if Earth had found a ZPM, they would dial Atlantis and let them know. After all, the SGC has no other use for a ZPM than to dial Atlantis.
Grumpy Scot