In "The Big Bang Theory (2007)": "The Pancake Batter Anomaly (2008)", Sheldon tells Penny that he was alone in Germany due to his mom having to return home due to tornado damage, because "the house had slipped off the cinder blocks again" due to it being an aluminum house. However, the Cooper house has always been a stick-built house and not aluminum nor on cinder blocks. Now that Sheldon is going on his Germany trip, this episode seems to be retconning it to Meemaw's house being destroyed instead (her house also being a stick-built house).
Age inconsistency: George Sr refers to Missy as being 13, yet in s01e01, Sheldon refers to himself as 9 years old. Because Missy and Sheldon are twins, they both would be 9 in season 1 and should both be 14 in season 6.
The exterior shot of Sheldon's aircraft in flight is of a Boeing 787 Dreamliner in the Continental livery, a model not introduced until 2009 and never flown by Continental Airlines. This episode takes place in the 1990s. EDIT: The aircraft type appears to be a 777, a type introduced in the mid-1990s. Continental operated several Boeing 777s from 1998.
Meemaw's house is completely destroyed, yet the house next door is unblemished (not even one missing shingle), as are the houses across the street. In addition, all the trees and shrubs in the background are intact and have all their foliage, instead of being broken and stripped bare by the wind.
After a tornado strikes, the streets and roads are covered with debris and impassable. It can take days to clear them. However, when Dale and Meemaw pull up to Meemaw's house in his truck, minutes after the tornado, the street is clean, clear and unobstructed.