Tropes on a Bus

http://static.tvtropes.org/pmwiki/pub/images/BenCohenTopsyTurvy3927w-740485.jpg
"...go round and round, round and round, round and round. The Tropes on a Bus..."

In trope-speak, a "bus" is a metaphorical device that effortlessly transports characters away from the plot for a long time. Often permanently.

Front-Line Fleet (tropes that directly reference the metaphorical bus).

Backup Fleet (these refer to buses, but not in that way).
http://tvtropes.org/pmwiki/pmwiki.php/Main/TropesOnABus