The explanation of the uncertainty principle in this episode has been confused with the so-called observer effect. Both are aspects of quantum mechanics, but the uncertainty principle states the impossibility to measure the value of some pairs of variables (so-called conjugate quantities) like location and speed of a particle at the same time with absolute certainty, while the observer effect states that observing an object always has an effect on the object.
Don and Charlie graduated high school on the same day.
When he was three, Charlie could multiply four digit numbers in his head.
Alan's wife, and Charlie and Don's mother, died of cancer.
First appearance of Susan Beaubian in her recurring role as Tech Agent Stendhauser, unnamed in this episode (credited as "Tech Agent #1").