You can uncomment and use this property in the IntroscopeAgent.profile to ignore the 404 errors:
# The following series of properties lets you specify error messages
# to ignore. For errors with messages matching these filters,
# error snapshots and error metrics will not be generated or sent.
# You may specify as many as you like (using .0, .1, .2 ...). You may use wildcards (*).
# The following are examples only.
# Changes to this property take effect immediately and do not require the managed application to be restarted.
#introscope.agent.errorsnapshots.ignore.1=*HTTP Error Code: 404*