It came after a forum that for the most part focused on the tough issues facing the city of Chicago.
The candidates also took issue with Rahm Emanuel and Gery Chico choosing to skip Saturday's gathering.
Moseley Braun was a no-show at an event Saturday night at the DuSable Museum commemorating the one-year anniversary of the Haiti earthquake.
Earlier, an internet blogger captured a heated exchange at Saturday morning's mayoral forum between Braun and candidate Walls.
Sparks flew after a voter asked each candidate why they were running for mayor only after current Chicago Mayor Richard Daley announced his retirement.
The heated exchange between mayoral candidates Moseley Braun and Walls lasted only a few minutes. The video shows the former aide to Harold Washington blasting the consensus African-American mayoral candidate calling her "broke and corrupt."
Moseley Braun then fired back, questioning why Walls wants to be mayor.
"Doc, you have run for mayor, your have run for senate," Moseley Braun said.
Soon after the panel's moderator diffused the tension, Moseley Braun returned the focus back to who actually attended the town hall-style meeting and who did not.
"The disagreements between us are less, frankly, then the things we agree on -- it's the empty chairs here," Moseley Braun said.
"They just had differences of opinion. That's what community forums are. That's why you have opportunities to hear from the candidates," del Valle said at the DuSable Museum event about Moseley Braun and Walls' exchange.
At the Saturday morning forum, the conversation had been about the issues -- mayoral candidate Miguel del Valle talked about reinvestment in neighborhoods.
"We need to make Chicago a small business friendly city," del Valle said.
Newly-known mayoral challenger Patricia Watkins addressed the topics of crime, government corruption and education.
"So my commitment is to fund community organizers," Watkins said.
Noticeably absent were mayoral frontrunners Chico and Emanuel, who drew the ire of some voters.
"I think Rahm Emanuel is just disrespecting us. I think he thinks he is going to come in on Obama's coattails," said voter Maire Smith.
Emanuel responded after greeting voters at a south side Target store and lunching with black ministers Saturday.
"I chose to be with the ministers today to be here to talk about their endorsement and our common challenges representing their congregations," Emanuel said.
"It's a Rose Garden strategy," del Valle said about Emanuel. "He, I'm sure, feels that he doesn't need to go out into the neighborhoods, that all he needs to do is shake hands at a few stops and spend millions of dollars on TV commercials."
Chico, who said he had a prior commitment, also did not attend the forum.
"There's only so many hours in the day, and I try to go to everything I can," Chico said. "Sometimes what happens is you have things that are pre-scheduled for a couple, three-weeks ahead, and you don't want to disappoint those people by not going to an event you've already committed to in order to make another one."