No way is that a painting. It might be shopped versions of the model since it was definitely something they had to crop into a background they made for their ad, but its less work to change the model than you think. Also Superman's head looks a bit different on the face too.
You can change in game model faces pretty easily actually. You use things called blend shapes to make all the mouth shapes and facial contortions you need for talking and phoneme's in either Maya, or 3DS max or the equivalent. Basically, what you do is clone the polygons for the head and stretch them into different positions by tugging on the vertices and then you can sort of select the new heads and the old one and then tell the model that these are all the same states for just one head. It stores the other head shapes you made and then you just setup controllers and sliders control their face with during animations. All those animations are then loaded into your game engine.
Long story short, you can contort someone's head polygons into a ton of different looks without affecting the texture negatively so long as the number of polygons doesn't change. I'm betting they got their feedback and went into her texture map in photoshop and brushed in some better makeup for the eyes and mouth and went into her model and tucked the vertices back some along the jawline and pulled out the polygons on her lips some more. Thing is her neck is super narrow. I know her hair make's up for it, but its kind of thin given how broad her shoulders are. When you draw women its usually 2.5 head widths from shoulder to shoulder for women and 3 to 3.5 for broad...she's nearly at 4.
Sorry, I got lost in the technical there for a moment but its kind of my profession now that I'm out of school.
