When Mary Cooper introduces herself as "Sheldon's mother" to Dr. Eric Gablehauser, Sheldon's boss, he says that's impossible and that she must've had Sheldon when she was a teenager. Laurie Metcalf is 17 years older than Jim Parsons.
When rehearsing what he is going to say to Dr. Gablehauser, Sheldon ends with "Mahalo." This is a Hawaiian word which loosely translates as "Thank you" but is also used to express admiration, gratitude or respect.
Sheldon's 'estimate' of 4,000 pounds for Penny's vehicle is grossly inaccurate. Modern mid-size sedans average 3,200 pounds while her small Volkswagen Golf Cabriolet weighs closer to 1,900-2,100 pounds.
Sheldon weaving on the loom is mentioned again in The Toast Derivation, where it is revealed that he made matching serapes for Leonard, Howard and Raj, the latter most of which who still wears it when the weather gets cold.