Wreck-Gar playing on an accordion is a reference to his voice actor, 'Weird Al' Yankovic and his favorite music instrument.
Wreck-Gar mentions he wanted to name the Triceratops Dinobot Slag originally, but he took it as an insult -- a double-reference to both the original Triceratops, who was called Slag (but the name had to be changed to Snarl for international ethical reasons); and that the word "slag" is a real insult in the Transformers' language.