Revealing mistakes: Instances where two characters played by 'Eddie Murphy' get too close to one another, the characters will sometimes mesh together. Most obvious is when Mama and Papa are hugging in kitchen.
Incorrectly regarded as goofs: While she's referred to as "Grandma Klump," which would be odd since it implies the same last name as her son-in-law, she gives her name as "Ida Mae Denson."
Revealing mistakes: When Sherman looks at his reflection in a glass window on a door and Buddy Love's face appears then disappears, the reflection is obviously a CGI because you cannot see through it.
Continuity: Professor Denise Gaines' Volkswagen backed up a couple of feet (by itself) outside the bridal shop from the time when she got inside it to when it started pulling away.
Continuity: When Papa Klump and Grandma are arguing at restaurant, the spaghetti in Grandma's hand changes between shots.
Continuity: Before Ernie asks for more wine at the family dinner, his plate is right in front of him. But as he turns to ask for the wine, the plate disappears and re-appears between shots.
Revealing mistakes: In the scene with the fireflies, for the full moon to be so close to the horizon, it would have to be close to sunrise or sunset, not late in the evening.