When Fathead is typing the computer in Sam's lab the T key is press repeatedly but the text on screen has no T's in it.
At the beginning of the episode it was stated that Lois's father Sam had moved back to Metropolis and was working there. It was also clear that when Lois's mom Ellen came to town she was staying with Sam. So at the end when all 4 parents came downstairs in pajamas there is no reason why Lois's parents would have been there in the middle of the night.
Klaus Mensa says that the average human uses less then 10% of his brain. This is actually an urban legend; scientific research has shown that humans use 100% of their brains at all times, even while asleep. If Mensa is using 98.6% of his brain, as he claims, this indicates not that he is extremely intelligent, but that he is suffering from severe brain damage.