Other mistake: In the opening scene, something catches the husband's eye through a window. He asks his wife to take a look and she gets scared. There is a dead body. When Lenny and Curtis arrive, and are lead back to the body, you can see the view from the street is obstructed. There is a display case, a pedestal, a vase and finally a wall. The head of the body wouldn't have been visible from the street and there was no other disturbance to catch someones attention: The husband and wife couldn't have seen anything.

Law & Order (1990)
1 other mistake in season 7 - chronological order
Executioner - S18-E9
Factual error: Yost attacks and kills an innocent man, believing him to be Dr. Horace Garrison, a physician who administered a faulty lethal injection to a condemned prisoner, reducing him to a vegetative state rather than killing him. The problem is, medical doctors never, ever participate in an execution except to certify death, a legal requirement. They do not, ever, take an active role in killing the condemned person.
Det. Lennie Briscoe: I'm trying to decide what to arrest you for - obstruction of justice, harboring a fugitive or just being a general pain in the ass.
Question: Why did Arthur fire Serena?
Answer: He believed that she had become too empathetic towards the defendant they had been prosecuting, and that her actions were driven by her emotions instead of facts. While empathy is a good quality in general, a certain degree of detachment is required in order for a prosecutor to do one's job effectively.





Suggested correction: I'm not sure where you're getting your information, but medical doctors are involved in lethal injections more than just certifying death. This is why so many groups were actively trying to stop the practice of medical profession involvement. In 2007, 17 states required physician involvement, which included doctors at times having to administer the injection.
Bishop73
The botched execution took place in South Carolina, which absolutely forbids medical practitioners to take an active role in killing a condemned prisoner. In fact, they are considering switching executing prisoners by firing squad instead of lethal injection, at least partly to distance medical professionals from the actual procedure leading to a person's death.