The moon is full, and is tinted gold indicating a harvest moon. In real life, it’s a rare phenomenon for a full moon on Halloween, happening every 19-20 years, while a harvest moon occurs normally in August or September.
Starla is seen without her cowgirl hat for the entire episode again, following Truck Rangers.
Some of the Monster Machines’ costumes are references to future episodes:
Crusher getting scared by a shadow of what he thinks is a monster.
Pickle changing his costume.
When Blaze says "We came, we sawed, we conquered" after destroying Crusher's Robo-Pumpkin Blaster and carving a real pumpkin, it is a reference to Julius Caesar's famous line "Veni, vidi, vici", which is Latin for "I came, I saw, I conquer".
"Truck or treat" is a pun on the Halloween term, "trick or treat".
When Crusher activates the Halloween candy stealer, it sucks up Darington's candy bucket (the bucket with candy corn on it). After Crusher says "I want more candy!", it sucks up the same bucket again.
There were six candy buckets (one for Blaze and each of his friends), but the Halloween candy stealer sucks them up more than five times, as if there were much more candy than that.
Therefor, the Halloween candy stealer shouldn't have exploded and sent the candy flying after all six buckets were sucked up.
When Crusher says "I want that candy!", Blaze's foglights are not lit.