Kylie refers to Marlin Perkins when dealing with the Vanguard of the Air. Perkins was a zoologist and host of "Mutual of Omaha's Wild Kingdom" from 1963 to 1985. Marlin Perkins was mentioned previously by Peter Venkman in It's a Jungle Out There (1987).
Inside the containment unit, the Ectoplasmic Owl from Darkness at Noon: Part 2 (1997) and The Pied Piper of Manhattan (1997) is visible after Slimer gets captured. Eduardo encounters Lotan from Moby Ghost (1997). Slimer is confronted with Banshee and Syren from Sonic Youth (1997).