Lisa is walking down the steps with Screech's heart on and asks, "Has anyone seen my Screechikins?" Screech replies from inside his locker, "I'm in here my Love Kitten." When Screech comes out of the locker, he is wearing his heart.
Mrs. Wentworth reveals the hidden subliminal message in her cassette tape to the class by "turning up the vocal track". of her voice. If her voice was so quiet that we couldn't hear it during the initial playing of the tape then it was too quiet for the students to hear and thus too quiet for their brains to register making it ineffective as a means to implant the subliminal message. Mrs. Wentworth's method is not how subliminal audio messages are implemented.
Screech's heart has his nickname on it, and not his actual first name ("Samuel").
All of the guys' hearts have their first names on them except for A.C Slater's which has his last name ("Slater") on it. This may have been because his full name of "Albert Clifford Slater" had not been established yet.