Plot hole: If the groom didn't know who Lois was but had a picture of her, how could he have known that she was at the wedding so he could place the bomb in the blue sedan? If he had put the bomb in their car while they were still at home, they both would have been blown up. So this means he placed the bomb in the car at the wedding. He didn't know however that Lois was there until the end, where he caught up with them and told them not to start the car. Had he known earlier, he wouldn't have been arguing with his bride about the hit occurring during their honeymoon.
Plot hole: As evidenced by the big bar room shootout, even if they couldn't die in this episode, wounds would still show up on your body (if shot with a gun, there would still be a hole). So, when Peter jumped off the building, when he hit the ground he should have been reduced to a fleshy puddle, even if he weren't dead.
Plot hole: Brian bets Stewie about being at high school for a week. However, this was before Peter's stroke, and before the fire at McBurgertown. It would take at least a few weeks for McBurgertown was rebuilt, then Peter had his stroke, and then Lois tells Chris Peter's stroke was 3 months ago. After this scene, Stewie tells Brian he has lost the bet. However, the bet would only last one week.
Plot hole: When it is revealed that Chris's teacher was never born, Teacher Doug introduces himself, despite the fact that if Chris's teacher was never born, Doug would already have been teacher for the entire year, and therefore all of the students should know him and he would not have to introduce himself.
Plot hole: Stewie gets out of the car seat and goes back to bed, leaving the blanket at the bottom of the seat. When they get to New York, Lois goes to get him out and realises he's gone. But when they started the trip the blanket was covering the entire seat to make it look like Stewie was still in it. So who ever "covered" him up knew he wasn't in the seat before they set off.
Plot hole: Brian and Peter see Loretta and Quagmire having sex yet, they aren't sure who she's having an affair with. There's no way they couldn't have noticed it was Quagmire - the couch was facing the front door! And obviously Quagmire was on top of Loretta considering the fact that he leans up, says something, then she tells him to get back down here and finish.