When Tobias is sitting in a chair complaining to Michael about his cease-and-desist letter from the Blue Man Group, a bowl of candy in his lap appears and disappears in different shots.
Tobias acquires a tranquilizer gun and cites the "gun show loophole" as to how he circumvented the waiting period. In reality the so-called "gun show loophole" only applies to private transfers of firearms. Purchasing one from a Federal Firearms License holder still requires a background check and a waiting period, regardless of the location of the sale.
It is stated that the charity auctions are a year apart, although in the last episode it is suggested that the whole series may have taken place within 53 weeks. However, the line is George-Micheal saying how long things have been going on between him and Maeby, which could be taken to mean their more recent affair, and not the entire run of the series. Also supporting this, besides the yearly charity auction, there are also multiple spring breaks and other such yearly occurrences seen in the show. Also, in the last episode, Micheal mentions making a choice three years ago to keep the family together.
When Michael and Gob are in the kitchen discussing Gob's new attachment to Lucille 2 and Michael says, "But yes I probably will tell people about this," Gob mistakenly starts to say his next line, "Maybe we can strike up a deal."