At 15:27, Jack moves his white king to A6 and there is a black knight at C6. Daniel's rook is at B8. But at 15:38, Daniel moves his B8 rook and it has somehow shifted into the C6 spot where the knight was just one move ago.
The doctors say that Daniel has no history of mental illness in his family, but later in Crystal Skull (2000) Daniel's grandfather had been put in a mental institution and deemed insane. However, a single instance of a psychiatric illness does not constitute 'a family history'. His mother (the daughter of the grandfather in question) is not recorded in the series as having had any mental illness.
When they first discover the 9 dead Goa'uld (at the start of the episode) you see Samantha Carter shining a flashlight across the character's back/neck to show the entry scar. Then as she is talking and moves towards the dead body's face, you can see the actor blink when the light is concentrated on his closed eyes.
When Carter puts the blood sample into the centrifuge, she doesn't balance the centrifuge before spinning the sample.
Daniel removes his glasses to put on the gas mask. It is obvious that his gas mask doesn't have corrective lens. These are wire frame lens that clip inside the eyepieces of the mask. It is standard procedure for anyone with corrective lenses and has a gas mask to have the custom lenses already in the mask.