In "What a Croc!", Phineas says, "They're wasting their time in that swampy marsh." This line is a reference to series co-creator Jeff "Swampy" Marsh.
Perry doesn't have a subplot in Ferb TV. Additionally, Ferb TV is also the first time Perry is never seen in his agent mode.
What a Croc implies that Phineas and Ferb (excluding the winter episodes) is not restricted to a single summer, because Dr. Doofenshmirtz said that his brother won a Best Mayor award for the 2nd year in a row, so this is a different summer from Hail Doofania when Roger was elected mayor.
Major Monogram is entirely absent physically, his voice only being heard in Ray Liotta's "The Academy" flashback. Dr. Doofenshmirtz is also only heard in voiceover in the credits of the Ferb TV segment.
Ferb TV: Fourth episode of Phineas and Ferb to have just one plot.