Continuity mistake: In the scene where Griffin is marketing the yellow sports car to a customer in the dealership, he laughs out loud while fooling around in one shot, and as the camera changes, his face is straight, and when it changes to the previous camera, he is laughing and fooling around again.
Continuity mistake: During the scene when they are trying to get a Red Bull can out of the Lion's throat, the saliva from the Lion is splattered on Griffin's forehead only, but as the camera cuts between angles, the saliva is splatter across his name badge and shirt, too. Change angle again, just the forehead, and back and forth during the whole scene.
Continuity mistake: When Gryffin is riding the little bike to get to the girl while being chased by the boyfriend, the flag on his bike changes colour between shots.
Continuity mistake: When Kevin James is biking with Gale, they get pushed into the main road. The same red minivan passes them 3 different times.
Answer: Most likely that learning that animals could always talk would be a big shock to them and they wouldn't know how to handle it.
What they're (Humans) gonna do if they can't?
Trainman
When a "reality that has always been true" (animals can't talk) turns out to be false, the world as adults knew it is suddenly turned upside-down, which causes stress. The things adults said in the presence of animals were actually understood by them when adults presumed they were not. This could cause anxiety, embarrassment, regret, and other "difficult to handle" emotions. Cruel words directed toward animals ("You're so ugly; "You're stupid") can't be taken back, which would be disturbing.
KeyZOid
The new reality would require a period of adjustment wherein adults would have to deal with and overcome their emotions and any past transgressions toward animals while learning to communicate more effectively and appropriately with them.
KeyZOid