Burnin' Down the House - S6-E1
Continuity mistake: Right before Will pours the liquid into the pot, you can plainly see a fire extinguisher on the counter behind him. It's gone when the fire is actually burning.
Burnin' Down the House - S6-E1
Continuity mistake: The cognac bottle is almost empty when Will passes by the counter, but when he turns around to pour the liquid, the bottle is full.
Answer: He's coming back from his vacation in Philadelphia.