“But there were some indignantly saying to one another…” This verse is hard to translate, and so the versions differ considerably. A literal rendition would be something like, “There were some being indignant with each other.” Of course, they were not being indignant with each other, they were indignant about what they now considered a waste of money, and were commenting to each other about it. Some versions say they were indignant “within themselves,” or “said to themselves,” but that can be misunderstood. The ones who were indignant were saying things among themselves, i.e., among their little disgruntled group, but not within their own minds and thus “talking to themselves.”
The Gospel of John lets us know that this verbal poison of grumbling and indignation started with Judas Iscariot, who was a thief and stole from the money that Jesus and the disciples received (John 12:4-6). From Judas this discontent spread through the room and infected some of the believers. Jesus cut it off quickly and decisively. “Let her alone…” etc. Christians need to learn from this record. A little evil (leaven) goes through the whole loaf of bread. We need to respond quickly to evil. [For more on Judas being a thief and starting the grumbling that infected the rest of the apostles, see commentary on John 12:4].