Tina's screams when Freddy kills her are on the sound effects tape Glen plays at the beginning

Good points.

It's details like these that make revisiting "Nightmare" so gratifying. Wes never gives us an answer as to what was real and what wasn't, leaving us to draw our own conclusions ... Maybe Nancy's not even a teen girl at all but instead some middle-age mental patient in a padded cell caught up in this alternate reality where she's Nancy, spunky high school student, who squares off against Freddy Krueger, child molester and killer, whose reign of terror results in the deaths of Nancy's three imaginary friends Glen, Rod and Tina ... Nancy could be herself the child molester and she created Freddy to rid herself of the burden of carrying around all the guilt she feels.