Bug in _removeModels: function(models, options) {

[Joc-Ne]

var index = this.indexOf(model); returns always -1
var index = this.models.indexOf(model) returns the right result

[jgonggrijp]

@Joc-Ne Thanks for reporting. Could this be a duplicate of #3882 and if so, does upgrading to Backbone 1.4.1 solve the issue for you? Otherwise, please provide a bit more context.