Corrected entry: It makes no sense why the Gecko brothers took the bank teller hostage at the beginning. Their plan was to get across the border into Mexico and to the rendezvous using the Fuller family, and their RV was perfect. But what was their original plan? Were they gonna have the hostage drive their car while they hid in the trunk? She would have given them up immediately. Also let's not forget that her face was on TV news programs which makes her a liability at the border gate. Basically there is no logical reason and all they would have done (if Richie didn't kill her) was create unneeded collateral.
Correction: They had Gloria hostage in case they had a run in with the police.
Correction: Criminals behaving illogically don't constitute a plot hole. The fact that Ritchie raped the bank teller may have been his motive for kidnapping her, rather than just killing her right away.
Bishop73
Also, Seth states at some point he does not take hostages (either on leaving Benny's world of liquor or after discovering the teller is dead, I can't remember where he said it) which suggests it was all Ritchie's idea to kidnap her and Seth didn't want, far less plan, to take a hostage, and that he felt it was unnecessary to do so.
The_Iceman
What Seth says is that he doesn't kill people that he doesn't have to, and he doesn't rape women. Which is what Richie just did to the hostage. Seth has no problem taking hostages, as we see in the very next scene when he takes an entire family hostage.
jshy7979