When Frank, Dee, and the corporate rep are at the gay bar the rep says that he has only stayed in his seat because Frank is pointing a gun at him. However, at the start of the scene you can see both of Frank's hands and he is not holding a gun.
When Frank, Dee, and the corporate rep are in the gay bar, they are shown from two angles. When the corporate rep is shown from the front, he has both a bottle of beer and a glass. When he is shown from the back, he has only the glass.
Dennis insists that Mac can't talk to potential customers because Mac has an exceptional number of bugs in his teeth, which can clearly be seen. Seconds later the three of them are singing to the customer and Mac's teeth are completely clean.