The Robinsons Were Here - S1-E4
Revealing mistake: After going beyond the perimeter fence for the first time, the children initially find the flowers that bloom when they each clap. When the robot motions to clap, you can see its left hand lost to the CGI flowers.
Shell Game - S2-E9
Revealing mistake: While Maureen and John are piloting their two maintenance pods, in the closeups which face each of them head-on, note the walls behind them have numerous identical smudges in their individual pods, which is especially noticeable in consecutive closeups.
Answer: Yes to all questions. The best theoretical estimate is that the universe is about 7 trillion light years across. That is about 250 times larger than the currently observable universe. So, yes, using trillions of light years as a unit of measure is appropriate. And, yes, the age of the universe is a measure of time, and the space between galaxies is a measure of distance.