Early in the school concert a girl dressed as an elf is on stage singing to a piano accompaniment, however Roxy the pianist is sitting at the piano but not playing it.
When Becca finds the iPod from Bert he is very pleasantly surprised when she calls him Grandpa and not Bert, however it wasn't the first time, she called him Grandpa at the audition when he was whooping and clapping.
In the scene where Becca has on a pink vest, when she is talking to Bert her hair is clearly messy, the next scene at school it is neatly braided in two braids.