The TARDIS automatically translates all languages so those linked to the TARDIS can understand and converse with all aliens, no matter what language they speak. However, in this episode, the TARDIS does not translate the Foamasi language (clicks, whistles and beeps), and The Doctor and Romana do not understand the Foamasi until the Foamasi gets a hold of a voice synthesizer and apparently switches to English.
Romana refers to a "FIFO stack", which is a contradiction. Stacks are FILO (first in last out) data structures, while queues are FIFO (first in first out).