Continuity mistake: Mary's glass of wine goes from being almost empty to about half full during her conversation with Charlotte. In the same scene Charlotte goes to put the bottle down but in the next shot she is still holding it.
Continuity mistake: In the scene where the F.B.I. storm Dick's house, Charlotte's sleeves change length (i.e. being pulled up or like normal) throughout the entire scene. (00:20:00 - 00:20:30)
Other mistake: In the scene where Don arrives at Dick's 'party', he looks at his non-existent watch. (00:13:25)
Answer: No, the IRS cannot make you pay taxes during years in which you had no income but this family hasn't reported any income for years. You are still required to report your income every year, and if you fall below a certain threshold you don't pay federal income taxes. The IRS is assuming they are humans who have a house and careers but they have only filed taxes for a couple years (if at all). To the IRS it looks like simple tax evasion.
BaconIsMyBFF