When M'yrnn first starts on his mac and cheese he has something green on his fork. After a cut he has something red, possibly a pepper.
When Mon-El and Kara are talking at the bar the position of Mon-El's bottle changes position with almost every shot, from in his hand, on the bar's countertop, and the distance between the bottles on the bar counter also changes.
After finding a lead to the copycat Toyman, Mary obtains a gun from the armory and leaves to follow it on her own. For such a top-secret, secure government agency like the DEO, it's highly unlikely that a civilian would not only know where the armory is, but be able to access it.
In one scene, J'onn reminds his father that, as a small house-warming party at their apartment, they have dinner plans with both Alex and Kara, but Kara remains on duty at the DEO the whole time and makes no attempt to take time off to join them.
While recounting the story of traveling to Disneyland, which his mother reveals was a pretense to try to escape from his father, Winn uses the redundant phrase "a.m. in the morning."