Continuity mistake: At the start of the film as Cady's Dad gives Cady her lunch bag, he has nothing round his neck. But in the next shot the camera is around his neck. (00:00:35)
Continuity mistake: When Cady is starting her first day of school and her parents are saying goodbye, she starts to walk up to the high school. Her dad starts to walk away while her mom stays standing there. In the next shot where it shows Cady's face, her mom and dad are still watching her together. (00:01:45)
Continuity mistake: On Cady's first day at her new school, she walks toward the front entrance through a crowd of kids. A black girl with a green comb in her hair approaches Cady from the right and passes without incident. Yet in the very next shot, the same girl again approaches Cady and purposely bumps into her. (00:01:50)
Continuity mistake: On Cady's first day of school, she introduces herself to a student who she thinks is the teacher. If you look directly behind them, there is a girl with a white sweater and blonde hair walking in front of the blackboard who almost reaches the end. The shot changes and the girl is farther away, then it happens again in the next shot. (00:02:10)
Continuity mistake: When Cady runs into her teacher on the first day of school and spills coffee all over her, look at Tina Fey's pants. It looks like she is wearing rubber pants when the coffee is spilling down her front. The color of the pants also change during this shot. (00:02:50)
Continuity mistake: When Cady comes home from her first day her father sets down his book on the notepad on the desk as he sees her. In the next shot as she goes inside the book has moved back. (00:05:20)
Continuity mistake: At the beginning of the second day of school, Janis jumps from toying with a pencil below her waist to above her shoulder. (00:05:30)
Continuity mistake: When Cady is outside on the field with Janice and Damian supposedly going to the back building, there is a very large shadow in front of the football uprights in the background (behind Cady) which keeps disappearing / reappearing. (00:06:15)
Continuity mistake: Between the first two shots of sex-ed on the second day of school, a key hanging around the coach's neck goes from hanging out of his tracksuit, to inside his tracksuit. (00:06:50)
Continuity mistake: When Regina is being carried by some boys on the field, her "R" necklace is hanging out of her blue P.E. shirt. When they put her down it is tucked under her shirt, then when she blows a kiss it is back out again. (00:07:40)
Continuity mistake: When Regina is asking Cady about her home schooling, Regina's hair starts to fall over her shoulder, then the shot changes and it is back behind her shoulder. (00:11:00)
Continuity mistake: In the opening shot of Cady in calculus class, as her voice-over says "I was so happy to get to math class", the big textbook sitting on her desk alternates from closed to open. This happens again after Cady says "So Cute..." (00:12:10)
Continuity mistake: When the Plastics spot Gretchen's crush, between shots Gretchen goes from having her arm by her side, to playing with her necklace. (00:16:35)
Continuity mistake: When the Plastics are at the mall and they spot Gretchen's crush with another girl, in one shot, Karen is playing with her watch, in the next shot her arms are folded. (00:17:25)
Continuity mistake: When in Regina's bedroom, Regina takes off her pink cardigan, and puts it on a couch, just before the Plastics examine themselves in the mirror. When Regina's mum brings in drinks for them though, the top is positioned much differently. (00:18:45)
Continuity mistake: At the Halloween party, Karen tilts her head as she ponders cousin relationships, but in the next shot she's upright again. (00:26:30)
Continuity mistake: After the Halloween party, when Cady walks into Damian and Janis' house, Damian gets scared and tosses all of the popcorn out of his bowl. In the next shot of Damian his bowl is full again. (00:29:05)
Continuity mistake: In the scene where Santa comes in with the candy cane gram, as the camera cuts on and off of Cady, you will notice that her hands move from on top of her desk to in her lap a couple of times. (00:34:50)
Continuity mistake: In the wake of the candy-cane grams, Gretchen's arms change from above her shoulders to on the desk. (00:35:00)
Continuity mistake: When Cady, Janice and Damian are in class talking about different things, like watching a movie, and Cady tells Janice she can't see her art show because she going to Madison etc., Cady is applying lip gloss. She holds a pocket mirror and in shots of the mirror you can see Cady holding the pink tube of lip gloss in the same hand, then when it cuts to wideshots, the tube isn't in her hand. The pink tube of lip gloss also has no lid on it, yet near the end of the scene a blue long lid appears on the pink tube. (00:49:10)
Answer: Precisely because he was sleeping with a student. Getting her pregnant would bring their affair out into the open and create a scandal for the whole nation to know what he was up to. Therefore safe sex was really important to him.
The_Iceman
True, but since he was spending time with her, he could make sure that birth control was being used (i.e. him using a condom). I think he was trying to appear "uptight" about sex, so he could be the least likely suspect.