The Omicronians sitting in the back change seats between each shot.
When Leela first discovers that Popplers are intelligent creatures, she throws Jrrr away and licks her fingers. There are five "finger-licking" sounds, even though she only has four fingers. The fourth finger-licking sound is the one with no movement to it. The fourth being the transition between licking her last finger and going to lick her thumb.
Although this is only speculation and unconfirmed, it is likely that whoever did the finger-licking sound effect simply licked their own hand, not thinking to skip a finger in order to match the four-fingered hands of the Futurama universe.
When the first batch of Popplers is sold and the sign starts working, it should count by twelve, as Popplers are sold in batches of twelve and it reads "over # Popplers served" and not "over # batches of Popplers served".
