use strict;
use warnings;

print("Get time1\n");
my $time1 = time();

BEGIN {
   print("Override\n");
   no warnings qw(redefine);
   *CORE::GLOBAL::time = sub { 4 };
}

print("Get time2\n");
my $time2 = time();

print($time1, "\n");
print($time2, "\n");
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Override
Get time1
Get time2
1238164958
4
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I don't think so, but here's one:

The items in perlfunc are actually operators. Overriding of these named operators is handled by the parser, not by the overridden operator. When the parser encounters a named operator such as time it normally places an invocation of the operator in the opcode tree.

$ perl -MO=Concise,-exec -e'time()'
1  <0> enter
2  <;> nextstate(main 1 -e:1) v
3  <0> time[t1] v                       <-- time operator
4  <@> leave[1 ref] vKP/REFC
-e syntax OK
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But when the operator has been overloaded, it places a subroutine invocation in the opcode tree instead.

$ perl -MO=Concise,-exec -e'BEGIN { *CORE::GLOBAL::time = sub {} } tim
+e()'
1  <0> enter
2  <;> nextstate(main 3 -e:1) v
3  <0> pushmark s
4  <#> gv[*CORE::GLOBAL::time] s        <-- sub name
5  <1> entersub[t2] vKS/TARG,1          <-- sub invocation
6  <@> leave[1 ref] vKP/REFC
-e syntax OK
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The same goes when overriding a named operator locally.

$ perl -MO=Concise,-exec -e'use subs qw( time ); time()'
1  <0> enter
2  <;> nextstate(main 12 -e:1) v
3  <0> pushmark s
4  <#> gv[*time] s                      <-- sub name
5  <1> entersub[t2] vKS/TARG,1          <-- sub invocation
6  <@> leave[1 ref] vKP/REFC
-e syntax OK
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Re^2: Where does time come from? CORE::GLOBAL:time no honored. (order) has an example.