When Penny is first quizzed upon the Robinsons' arrival on Planet Delta, she is given a multiple choice question about the intensity of the sky's blueness. After finding out her answer was wrong, she is told the correct answer - which is not one of the original 3 choices.
When Dr. Smith leaves the room the pool table is filled with balls. When Bartholomew and his crew enter the room a short while later to perform the transfusions, the balls have been completely cleared from the table.
When the Jupiter 2 lands and takes off a circular pattern painted on the ground with the number 115 is seen. But during other external shots of the Jupiter 2 this landing marking is not present.
The robot reminds Professor Robinson what Will told him to do with the memory sticks, but he was not present when Will told his dad to "light them up".
When Professor Robinson doesn't recognize Will as his son, Will says: "I've always called you Dad." Professor Robinson replies: "It would be alright for you to call me Dad, if you were my son." After the Professor lights up the memory cones, his reply to Will is repeated, but incorrectly. He now says: "It would be alright for you to call me Dad, if I was your father." The is also grammatically incorrect, which would be unusual for Professor Robinson.
The music played in the young people's disco is in 60s pop style. The Robinson children should recognize it as music from the past, specifically the era when their parents would have been teenagers. It would not sound modern to their ears.