When the turtles go with April to watch the tape, Raphael's red bandanna, arm bands, and knee pads turn blue like Leonardo's.
In this episode Baxter Stockman easily finds Splinter in the Turtles lair, however in subsequent episodes Shredder tries to locate the Turtles lair but can't find it.
When Michelangelo says "What's the haps" his mouth doesn't move.
When the turtles are talking at the dinner table near the beginning Raphael when talks about how the ooze mutated Splinter he speaks in Leonardo's voice.