Grails has some useful tags for rendering errors of an object in a view. Below we see an example whichs renders the errors for a single bean.

<g:hasErrors bean="${person}">
       <g:renderErrors bean="${person}"/>

However an undocumented feature of these tags is the possibility to provide a map so we can render errors of multiple beans. See the example below:

<g:hasErrors beans="[person: person, order: order]">
       <g:renderErrors beans="[person: person, order: order]" as="list"/>

Tested with Grails 2.4.4.