Adapted from the popular Superman story "For the Man Who Has Everything" by Alan Moore. The effects of the Black Mercy on Supergirl are the same as on Superman in the two-part Justice League Unlimited episode "For the Man Who Has Everything". The only difference that it was Mongul that used the Black Mercy on Superman, and Non used it on Supergirl.
When Supergirl confronts Non, she reacts the same way that Superman did with Mongul in the series "Justice League." Mongul trapped Superman with the Black Mercy on his birthday and when Supes confronted Mongul, he lead with the same words as Kara did with Non- "Do you have any idea what you did to me?!"
First appearance of Kal-El, not as a baby, or as Superman.
The largest geomagnetic or solar storm in history was the Carrington event in 1859. Power surges in wires were so strong that telegraph systems all over the world were disabled. There were cases of telegraph operators being shocked by the discharges, which even started fires. Telegraph pylons threw sparks. Some telegraph operators could continue to send and receive messages despite having disconnected their power supplies. Auroras were observed all over the world; places as far north as Queensland in Australia and sub-Saharan Africa, and as far south as the Caribbean. Those over the Rocky Mountains in the U.S. were so bright that the glow woke gold miners, who began preparing breakfast because they thought it was morning. People in the northeastern United States could read a newspaper by the aurora's light.
If the solar storm mentioned in the episode was even close to the same scale, it would have probably put out all communications and electronic media across much of the world, as well as killed power across the entire US.
The parasite attached to Kara is called a "Black Mercy". It makes its victim docile by allowing them to live out an idyllic fantasy life while the parasite feeds.