The role of Stacey Thompson was to be originally played by Alexa PenaVega, but a scheduling conflict with her film, Broken Hill (2009), which was filmed in Australia lead to her having to be recast, Kat Dennings was cast instead.
During the initial classroom scene when the teacher is conducting an experiment with catalysts, the "blink contest" girl blinks in a brief moment wherein the aliens are circling the bottoms of the classroom desks, ruining her record.
Blinker #1 blinks (at around 31 mins) while opening a cellophane bag over his cereal bowl. Blinker #2 blinks (at around 22 mins) in the background during the classroom scene where the aliens are circling the bottoms of the students' desks while the teacher is conducting an experiment with catalysts.
Near the end of "The Miscommunicators" party, Helvetica says "I wish these casts were off" and the camera cuts (01:05:39) to Toe marveling that his arms no longer have casts, but at the right edge of the frame Helvetica's right arm is still shown in a cast and holding the wishing rock. At 01:05:41 she adds "Not his, just mine", at which point the camera cuts to a shot of Helvetica without casts while behind her Toe's arms are in casts again.