The song that Cruella heard from the radio that she stole is a jazz instrumental version of "Cruella De Vil" from One Hundred and One Dalmatians (1961).
The episode title is a reference to the Rolling Stones song "Sympathy for the Devil."
The poisonous trumpet flower is probably Angel Trumpet (Brugmansia). These strikingly dramatic looking and thoroughly toxic plants are also very fragrant.
Milli Wilkinson, the actress that plays the child version of Cruella also played Alice's daughter in And They Lived... (2014).