Stupidity: Early on in the show Tony had a rule about talking business on the phones. He even scolded Tony Blundeto about talking too boldly on the phone. Now he's speaking with Sil on a phone openly about the FBI finding a body from 25 years ago. If the government is listening in he gave them all the ammunition they need to focus their probe. Even when they speak in code, the government has experts that decipher it and testify to its nature. They even used names which help identify the parties involved. (00:21:16 - 00:22:00)
Stupidity: The cops find Corado Soprano, aka Junior, wandering the streets because he is experiencing dementia. His family doesn't know of his illness yet. The police take him inside their vehicle without searching or handcuffing him. The back of their cruiser has no protective shield. They just put their lives in jeopardy by not checking him for weapons. Just because somebody doesn't pose an immediate threat doesn't mean they won't become violent later and pull a weapon and stab or shoot them. (00:39:34 - 00:40:42)
Stupidity: Paulie and an associate just killed 2 drug dealers or stash house guards, and they are rummaging throughout the apartment touching appliances and other surfaces without any gloves. Paulie was previously arrested and did time so his fingerprints are on file. Paulie also used a knife to stab one of the Colombians without any gloves on, and he just left it in his body. The police would have no problem linking him to this crime within a week after forensics did their sweep. (00:03:00 - 00:04:17)