I've played this multiple times before and don't remember coming across this question, but last night we couldn't remember how it worked, and couldn't find anything in the rules one way or the other.
If someone chooses a truck in phase 1, then there will be a men of action card leftover at the end of the round. Does this card stay there for next round, or is it discarded to make room for all new cards?
If the rules don't say to discard it, then it seems that the default would be to leave it; but the rules for dealing out new cards at the start of each round sound like you're always dealing out 1 per player.
The un-selected Men of Action card would be discarded. Only the truck would remain for the next turn if un-selected. This is on page 7 of the current rules.