Maleficent did hear with her elf ears that Kili was in pain, but she didn't want to make herself too worried. She did keep eyes and ears on the twins now, since everyone here was defenseless. 

[i]Girion, the lord of the city, rallied his bowmen to fire upon the beast. But a dragon’s hide is tough, tougher than the strongest armor. Only a Black Arrow fired from a wind-lance could have pierced the dragon’s hide. And few of those arrows were ever made. The store was running low when Girion made his last stand[/i].

Visuals of that time were being in the heads of all who heard the tale. The arrow missing the dragon's hide, whilst not piercing it. "If the aim of men had been true that day, much would’ve been different", Thorin grimly remarked while he looked to the Hobbit and his old friend. 

Following the same trail of the company, Legolas finds his cousin standing in the distance, while pointing his arrow at her.